Processes based on atom (or group) transfer radical polymerization and novel (co) polymers having useful structures and properties

ABSTRACT

Improved processes have been developed for atom (or group) transfer radical polymerization (ATRP). In one improvement, the ATRP process involves polymerizing in the presence of a (partially) free radical-deactivating amount of the corresponding reduced or oxidized transition metal compound. In a further improvement, the ATRP process involves polymerizing in a homogeneous system or in the presence of a solubilized initiating/catalytic system. The present invention also concerns end-functional, site-specific functional and telechelic homopolymers and copolymers; block, random, graft, alternating and tapered (or &#34;gradient&#34;) copolymers which may have certain properties or a certain novel structure; star, comb and &#34;hyperbranched&#34; polymers and copolymers; multi-functional hyperbranched, end-functional polymers; cross-linked polymers and gels; water-soluble polymers and hydrogels (e.g., a copolymer prepared by radical copolymerization of a water-soluble monomer and a divinyl monomer); and an ATRP process using water as a medium.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns novel (co)polymers and a novel radicalpolymerization process based on transition metal-mediated atom or grouptransfer polymerization ("atom transfer radical polymerization").

2. Discussion of the Background

Living polymerization renders unique possibilities of preparing amultitude of polymers which are well-defined in terms of moleculardimension, polydispersity, topology, composition, functionalization andmicrostructure. Many living systems based on anionic, cationic andseveral other types of initiators have been developed over the past 40years (see O. W. Webster, Science, 251, 887 (1991)).

However, in comparison to other living systems, living radicalpolymerization represented a poorly answered challenge prior to thepresent invention. It was difficult to control the molecular weight andthe polydispersity to achieve a highly uniform product of desiredstructure by prior radical polymerization processes.

On the other hand, radical polymerization offers the advantages of beingapplicable to polymerization of a wide variety of commercially importantmonomers, many of which cannot be polymerized by other polymerizationprocesses. Moreover, it is easier to make random copolymers by radicalpolymerization than by other (e.g., ionic) polymerization processes.Certain block copolymers cannot be made by other polymerizationprocesses. Further, radical polymerization processes can be conducted inbulk, in solution, in suspension or in an emulsion, in contrast to otherpolymerization processes.

Thus, a need is strongly felt for a radical polymerization process whichprovides (co)polymers having a predetermined molecular weight, a narrowmolecular weight distribution (low "polydispersity"), various topologiesand controlled, uniform structures.

Three approaches to preparation of controlled polymers in a "living"radical process have been described (Greszta et al, Macromolecules, 27,638 (1994)). The first approach involves the situation where growingradicals react reversibly with scavenging radicals to form covalentspecies. The second approach involves the situation where growingradicals react reversibly with covalent species to produce persistentradicals. The third approach involves the situation where growingradicals participate in a degenerative transfer reaction whichregenerates the same type of radicals.

There are some patents and articles on living/controlled radicalpolymerization. Some of the best-controlled polymers obtained by"living" radical polymerization are prepared with preformed alkoxyaminesor are those prepared in situ (U.S. Pat. No. 4,581,429; Hawker, J. Am.Chem. Soc., 116, 11185 (1994); Georges et al, WO 94/11412; Georges etal, Macromolecules, 26, 2987 (1993)). A Co-containing complex has beenused to prepare "living" polyacrylates (Wayland, B. B., Pszmik, G.,Mukerjee, S. L., Fryd, M. J. Am. Chem. Soc., 116, 7943 (1994)). A"living" poly(vinyl acetate) can be prepared using an Al(i-Bu)₃ :Bpy:TEMPO initiating system (Mardare et al, Macromolecules, 27, 645(1994)). An initiating system based on benzoyl peroxide and chromiumacetate has been used to conduct the controlled radical polymerizationof methyl methacrylate and vinyl acetate (Lee et al, J. Chem. Soc.Trans. Faraday Soc. I, 74, 1726 (1978); Mardare et al, Polym. Prep.(ACS), 36(1) (1995)).

However, none of these "living" polymerization systems include an atomtransfer process based on a redox reaction with a transition metalcompound.

One paper describes a redox iniferter system based on Ni(O) and benzylhalides. However, a very broad and bimodal molecular weight distributionwas obtained, and the initiator efficiency based on benzyl halides usedwas about 1-2% or less (T. Otsu, T. Tashinori, M. Yoshioka, Chem.Express 1990, 5(10), 801). Tazaki et al (Mem. Fac. Eng., Osaka CityUniv., vol. 30 (1989), pages 103-113) disclose a redox iniferter systembased on reduced nickel and benzyl halides or xylylene dihalides. Theexamples earlier disclosed by Tazaki et al do not include a coordinatingligand. Tazaki et al also disclose the polymerization of styrene andmethyl methacrylate using their iniferter system.

These systems are similar to the redox initiators developed early(Bamford, in Comprehensive Polymer Science, Allen, G., Aggarwal, S. L.,Russo, S., eds., Pergamon: Oxford, 1991, vol. 3, p. 123), in which thesmall amount of initiating radicals were generated by redox reactionbetween (1) RCHX₂ or RCX₃ (where X═Br, Cl) and (2) Ni(O) and othertransition metals. The reversible deactivation of initiating radicals byoxidized Ni is very slow in comparison with propagation, resulting invery low initiator efficiency and a very broad and bimodal molecularweight distribution.

Bamford (supra) also discloses a Ni P(OPh)₃ !₄ /CCl₄ or CBr₄ system forpolymerizing methyl methacrylate or styrene, and use of Mo(CO)_(n) toprepare a graft copolymer from a polymer having a brominated backboneand as a suitable transition metal catalyst for CCl₄, CBr₄ or CCl₃ CO₂Et initiators for polymerizing methyl methacrylate. Organic halidesother than CCl₄ and CBr₄ are also disclosed. Mn₂ (CO)₁₀ /CCl₄ is taughtas a source of CCl₃ radicals. Bamford also teaches that systems such asMn(acac)₃ and some vanadium (V) systems have been used as a source ofradicals, rather than as a catalyst for transferring radicals.

A number of the systems described by Bamford are "self-inhibiting"(i.e., an intermediate in initiation interferes with radicalgeneration). Other systems require coordination of monomer and/orphotoinitiation to proceed. It is further suggested that photoinitiatingsystems result in formation of metal-carbon bonds. In fact, Mn(CO)₅ Cl,a thermal initiator, is also believed to form Mn--C bonds under certainconditions.

In each of the reactions described by Bamford, the rate of radicalformation appears to be the rate-limiting step. Thus, once a growingradical chain is formed, chain growth (propagation) apparently proceedsuntil transfer or termination occurs.

Another paper describes the polymerization of methyl methacrylate,initiated by CCl₄ in the presence of RuCl₂ (PPh₃)₃. However, thereaction does not occur without methylaluminumbis(2,6-di-tert-butylphenoxide), added as an activator (see M. Kato, M.Kamigaito, M. Sawamoto, T. Higashimura, Macromolecules, 28, 1721(1995)).

U.S. Pat. No. 5,405,913 (to Harwood et al) discloses a redox initiatingsystem consisting of Cu^(II) salts, enolizable aldehydes and ketones(which do not contain any halogen atoms), various combinations ofcoordinating agents for Cu^(II) and Cu^(I), and a strong amine base thatis not oxidized by Cu^(II). The process of Harwood et al requires use ofa strong amine base to deprotonate the enolizable initiator (thusforming an enolate ion), which then transfers a single electron toCu^(II), consequently forming an enolyl radical and Cu^(I). The redoxinitiation process of Harwood et al is not reversible.

In each of the systems described by Tazaki et al, Otsu et al, Harwood etal and Bamford, polymers having uncontrolled molecular weights andpolydispersities typical for those produced by conventional radicalprocesses were obtained (i.e., >1.5). Only the system described by Katoet al (Macromolecules, 28, 1721 (1995)) achieves lower polydispersities.However, the polymerization system of Kato et al requires an additionalactivator, reportedly being inactive when using CCl₄, transition metaland ligand alone.

Atom transfer radical addition, ATRA, is a known method forcarbon-carbon bond formation in organic synthesis. (For reviews of atomtransfer methods in organic synthesis, see Curran, D. P. Synthesis,1988, 489; Curran, D. P. in Free Radicals in Synthesis and Biology,Minisci, F., ed., Kluwer: Dordrecht, 1989, p. 37; and Curran, D. P. inComprehensive Organic Synthesis, Trost, B. M., Fleming, I., eds.,Pergamon: Oxford, 1991, Vol. 4, p. 715.) In a very broad class of ATRA,two types of atom transfer methods have been largely developed. One ofthem is known as atom abstraction or homolytic substitution (see Curranet al, J. Org. Chem., 1989, 54, 3140; and Curran et al, J. Am. Chem.Soc., 1994, 116, 4279), in which a univalent atom (typically a halogen)or a group (such as SPh or SePh) is transferred from a neutral moleculeto a radical to form a new σ-bond and a new radical in accordance withScheme 1 below: ##STR1##

In this respect, iodine atom and the SePh group were found to work verywell, due to the presence of very weak C--I and C--SePh bonds towardsthe reactive radicals (Curran et al, J. Org. Chem. and J. Am. Chem.Soc., supra). In earlier work, the present inventors have discoveredthat alkyl iodides may induce the degenerative transfer process inradical polymerization, leading to a controlled radical polymerizationof several alkenes. This is consistent with the fact that alkyl iodidesare outstanding iodine atom donors that can undergo a fast andreversible transfer in an initiation step and degenerative transfer in apropagation step (see Gaynor et al, Polym. Prep. (Am. Chem. Soc., Polym.Chem. Div.), 1995, 36(1), 467; Wang et al, Polym. Prep. (Am. Chem. Soc.,Polym. Chem. Div.), 1995, 36(1), 465; Matyjaszewski et al,Macromolecules, 1995, 28, 2093). By contrast, alkyl bromides andchlorides are relatively inefficient degenerative transfer reagents.

Another atom transfer method is promoted by a transition metal species(see Bellus, D. Pure & Appl. Chem. 1985, 57, 1827; Nagashima, H.; Ozaki,N.; Ishii, M.; Seki, K.; Washiyama, M.; Itoh, K. J. Org. Chem. 1993, 58,464; Udding, J. H.; Tuijp, K. J. M.; van Zanden, M. N. A.; Hiemstra, H.;Speckamp, W. N. J. Org. Chem. 1994, 59, 1993; Seijas et al, Tetrahedron,1992, 48(9), 1637; Nagashima, H.; Wakamatsu, H.; Ozaki, N.; Ishii, T.;Watanabe, M.; Tajima, T.; Itoh, K. J. Org. Chem. 1992, 57, 1682; Hayes,T. K.; Villani, R.; Weinreb, S. M. J. Am. Chem. Soc. 1988, 110, 5533;Hirao et al, Syn. Lett., 1990, 217; and Hirao et al, J. Synth. Org.Chem. (Japan), 1994, 52(3), 197; Iqbal, J; Bhatia, B.; Nayyar, N. K.Chem. Rev., 94, 519 (1994); Asscher, M., Vofsi, D. J. Chem. Soc. 1963,1887; and van de Kuil et al, Chem. Mater., 1994, 6, 1675). In thesereactions, a catalytic amount of transition metal compound acts as acarrier of the halogen atom in a redox process.

Initially, the transition metal species, M_(t) ^(n), abstracts halogenatom X from the organic halide, R-X, to form the oxidized species, M_(t)^(n+1) X, and the carbon-centered radical R⁻. In the subsequent step,the radical, R⁻, reacts with alkene, M, with the formation of theintermediate radical species, R--M⁻. The reaction between M_(t) ^(n+1) Xand R--M⁻ results in the target product, R--M--X, and regenerates thereduced transition metal species, M_(t) ^(n), which further reacts withR--X and promotes a new redox process.

The high efficiency of transition metal-catalyzed atom transferreactions in producing the target product, R--M--X, in good to excellentyields (often >90%) may suggest that the presence of an M_(t) ^(n)/M_(t) ^(n+1) cycle-based redox process can effectively compete with thebimolecular termination reactions between radicals (see Curran,Synthesis, in Free Radicals in Synthesis and Biology, and inComprehensive organic Synthesis, supra). However, the mere presence of atransition metal compound does not ensure success in telomerization orpolymerization, even in the presence of initiators capable of donating aradical atom or group. For example, Asscher et al (J. Chem. Soc., supra)reported that copper chloride completely suppresses telomerization.

Furthermore, even where a transition metal compound is present andtelomerization or polymerization occurs, it is difficult to control themolecular weight and the polydispersity (molecular weight distribution)of polymers produced by radical polymerization. Thus, it is oftendifficult to achieve a highly uniform and well-defined product. It isalso often difficult to control radical polymerization processes withthe degree of certainty necessary in specialized applications, such asin the preparation of end functional polymers, block copolymers, star(co)polymers, etc. Further, although several initiating systems havebeen reported for "living"/controlled polymerization, no general pathwayor process for "living"/ controlled polymerization has been discovered.

Copolymerization of electron-donor type monomers (unsaturatedhydrocarbons, vinyl ethers, etc.) with electron acceptor type monomers(acrylates, methacrylates, unsaturated nitriles, unsaturated ketones,etc.) in the presence of monomer complexing agents (ZnCl₂, Et₃ Al₂ Cl₃,etc.) yield highly, if not strictly alternating copolymers (Hirooka etal, J. Polym. Sci. Part B, 5, 47 (1967); Furukawa et al, Rubber Chem.Technol., 51(3), 601 (1979)). The copolymerization succeeded, however,only if the polar monomer was significantly complexed by the Lewis acid.Further, the copolymerization was often initiated spontaneously, thusyielding very high molecular weight products having broadpolydispersities. The mechanism of this reaction is controversial andthere are suggestions that it is due to a complex (Hirai, J. Polym. Sci.Macromol. Rev., 11, 47 (1976)) or to enhanced cross-propagation rates(Bamford et al, J. Polym. Sci. Polym. Lett. Ed., 19, 229 (1981) and J.Chem. Soc. Faraday Trans. 1, 78, 2497 (1982)).

In the radical copolymerization of isobutylene (IB) and acrylic esters,the resulting copolymers contain at most 20-30% of IB and have lowmolecular weights because of degradative chain transfer of IB (U.S. Pat.Nos. 2,411,599 and 2,531,196; and Mashita et al, Polymer, 36, 2973(1995).

Conjugated monomers such acrylic esters and acrylonitrile react withdonor monomers such as propylene, isobutylene, styrene in the presenceof alkylaluminum halide to give 1:1 alternating copolymers (Hirooka etal, J. Polym. Sci. Polym. Chem., 11, 1281 (1973)). The alternatingcopolymer was obtained when Lewis acid!₀ / acrylic esters!₀ ═0.9 andIB!₀ > acrylic esters!₀. The copolymer of IB and methyl acrylate (MA)obtained by using ethyl aluminum sesquichloride and 2-methyl pentanoylperoxide as an initiating system is highly alternating, with either low(Kuntz et al, J. Polym. Sci. Polym. Chem., 16, 1747 (1978)) or high(60%) isotacticity in the presence of EtAlCl₂ (10 molar % relative toMA) at 50° C. (Florjanczyk et al, Makromol. Chem., 183, 1081 (1982)).

Recently, alkyl boron halide was found to have a much higher activitythan alkyl aluminum halide in alternating copolymerization of IB andacrylic esters (Mashita et al, Polymer, 36, 2983 (1995)). Thepolymerization rate has a maximum at about -50° C. and decreasedsignificantly above 0° C. The copolymerization is controlled by O₂ interms of both rate and molecular weight. The alternating copolymer wasobtained when IB!₀ > Acrylic esters!₀. Stereoregularity was consideredto be nearly random. The copolymer is an elastomer of high tensilestrength and high thermal decomposition temperature. The oil resistanceis very good, especially at elevated temperatures, and the hydrolysisresistance was excellent compared to that of the correspondingpoly(acrylic ester)s (Mashita et al, supra).

Dendrimers have recently received much attention as materials with novelphysical properties (D. A. Tomalia, A. M. Naylor, W. A. G. III, Angew.Chem., Int. Ed. Engl. 29, 138 (1990); J. M. J. Frechet, Science 263,1710 (1994)). These polymers have viscosities lower than linear analogsof similar molecular weight, and the resulting macromolecules can behighly functionalized. However, the synthesis of dendrimers is nottrivial and requires multiple steps, thus generally precluding theircommercial development.

Polymers consisting of hyperbranched phenylenes (O. W. Webster, Y. H.Kim, J. Am. Chem. Soc. 112, 4592 (1990) and Macromolecules 25, 5561(1992)), aromatic esters (J. M. J. Frechet, C. J. Hawker, R. Lee, J. Am.Chem. Soc., 113, 4583 (1991)), aliphatic esters (A. Hult, E. Malmstrom,M. Johansson, J. Polym. Sci. Polym. Ed. 31, 619 (1993)), siloxanes (L.J. Mathias, T. W. Carothers, J. Am. Chem. Soc. 113, 4043 (1991)), amines(M. Suzuki, A. Li, T. Saegusa, Macromolecules 25, 7071 (1992)) andliquid crystals (V. Percec, M. Kawasumi, Macromolecules 25, 3843 (1992))have been synthesized in the past few years.

Recently, a method has been described by which functionalized vinylmonomers could be used as monomers for the synthesis of hyperbranchedpolymers by a cationic polymerization (J. M. J. Frechet, et al., Science269, 1080 (1995)). The monomer satisfies the AB₂ requirements forformation of hyperbranched polymers by the vinyl group acting as thedifunctional B group, and an additional alkyl halide functional group asthe A group. By activation of the A group with a Lewis acid,polymerization through the double bond can occur. In this method,3-(1-chloroethyl)-ethenylbenzene was used as a monomer and wascationically polymerized in the presence of SnCl₄.

A need is strongly felt for a radical polymerization process whichprovides (co)polymers having a predictable molecular weight and acontrolled molecular weight distribution ("polydispersity"). A furtherneed is strongly felt for a radical polymerization process which issufficiently flexible to provide a wide variety of products, but whichcan be controlled to the degree necessary to provide highly uniformproducts with a controlled structure (i.e., controllable topology,composition, stereoregularity, etc.), many of which are suitable forhighly specialized uses (such as thermoplastic elastomers,end-functional polymers for chain-extended polyurethanes, polyesters andpolyamides, dispersants for polymer blends, etc.).

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to provide a novelmethod for radical polymerization of alkenes based on atom transferradical polymerization (ATRP), which provides a level of molecularcontrol over the polymerization process presently obtainable only byliving ionic or metathesis polymerization, and which leads to moreuniform and more highly controllable products.

A further object of the present invention is to provide novelimprovements to a method for radical polymerization of alkenes based onatom transfer radical polymerization (ATRP), which increases initiatorefficiencies and process yields, and improves product properties.

A further object of the present invention is to provide a broad varietyof novel (co)polymers having more uniform properties than those obtainedby conventional radical polymerization.

A further object of the present invention is to provide novel(co)polymers having new and useful structures and properties.

A further object of the present invention is to provide a process forradically polymerizing a monomer which is adaptable to use with existingequipment.

A further object of the present invention is to provide a method forproducing a (co)polymer which relies on readily available startingmaterials and catalysts.

A further object of the present invention is to provide (co)polymershaving a wide variety of compositions (e.g., random, alternating,tapered, end-functional, telechelic, etc.) and topologies (block, graft,star, dendritic or hyperbranched, comb, etc.) having controlled, uniformand/or well-defined structures and properties.

A further object of the present invention is to provide a novel methodfor radically polymerizing a monomer which can use water as a solventand which provides novel water-soluble (co) polymers.

A further object of the present invention is to provide novel(co)polymers which are useful as gels and hydrogels, and to providenovel methods for making such (co)polymers.

A further object of the present invention is to provide novel(co)polymers which are useful in a wide variety of applications (forexample, as adhesives, asphalt modifiers, in contact lenses, asdetergents, diagnostic agents and supports therefor, dispersants,emulsifiers, elastomers, engineering resins, viscosity index improvers,in ink and imaging compositions, as leather and cement modifiers,lubricants and/or surfactants, with paints and coatings, as paperadditives and coating agents, as an intermediate for preparing largermacromolecules such as polyurethanes, as resin modifiers, in textiles,as water treatment chemicals, in the chemical and chemical wasteprocessing, composite fabrication, cosmetics, hair products, personalcare products in plastics compounding as, for example, an antistaticagent, in food and beverage packaging, pharmaceuticals as, e.g., abulking agent, "slow release" or sustained release compounding agent!,in rubber, and as a preservative).

These and other objects of the present invention, which will be readilyunderstood in the context of the following detailed description of thepreferred embodiments, have been provided in part by a novel controlledprocess of atom (or group) radical transfer polymerization, comprisingthe steps of:

polymerizing one or more radically polymerizable monomers in thepresence of an initiating system comprising:

an initiator having a radically transferable atom or group,

a transition metal compound which participates in a reversible redoxcycle (i.e., with the initiator),

an amount of the redox conjugate of the transition metal compoundsufficient to deactivate at least some initially-formed radicals, and

any N-, O-, P- or S- containing ligand which coordinates in a σ-bond orany carbon-containing ligand which coordinates in a π-bond to thetransition metal, or any carbon-containing ligand which coordinates in acarbon-transition metal σ-bond but which does not form a carbon-carbonbond with said monomer under the polymerizing conditions,

to form a (co)polymer, and

isolating the formed (co)polymer;

and, in part, by novel (co)polymers prepared by atom (or group) radicaltransfer polymerization.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a variety of different polymer topologies, compositions andfunctionalizations which can be achieved by the present invention, butto which the present invention is not restricted;

FIG. 2 shows a comparison of mechanisms, exemplary kinetic parametersand product properties of conventional radical polymerization with thepresent "living"/controlled radical polymerization;

FIGS. 3A-B are plots of molecular weight (M_(n)) and polydispersities(M_(w) /M_(n)) vs. time (FIG. 3A) and of the instantaneous compositionof the copolymer (F_(inst)) vs. chain length (FIG. 3B) for the gradientcopolymerization of Example 16 below;

FIGS. 4A-B are plots of molecular weight (M_(n)) and polydispersities(M_(w) /M_(n)) vs. time (FIG. 4A) and of the instantaneous compositionof the copolymer (F_(inst)) vs. chain length (FIG. 4B) for the gradientcopolymerization of Example 17 below;

FIGS. 5A-B are plots of molecular weight (M_(n)) and polydispersities(M_(w) /M_(n)) vs. time (FIG. 5A) and of the instantaneous compositionof the copolymer (F_(inst)) vs. chain length (FIG. 5B) for the gradientcopolymerization of Example 18 below;

FIGS. 6A-B are plots of molecular weight (M_(n)) and polydispersities(M_(w) /M_(n)) vs. time (FIG. 6A) and of the instantaneous compositionof the copolymer (F_(inst)) vs. chain length (FIG. 6B) for the gradientcopolymerization of Example 19 below;

FIGS. 7A-B are plots of molecular weight (M_(n)) and polydispersities(M_(w) /M_(n)) vs. time (FIG. 7A) and of the instantaneous compositionof the copolymer (F_(inst)) vs. chain length (FIG. 7B) for a gradientcopolymerization described in Example 20 below;

FIGS. 8A-B are plots of molecular weight (M_(n)) and polydispersities(M_(w) /M_(n)) vs. time (FIG. 8A) and of the instantaneous compositionof the copolymer (F_(inst)) vs. chain length (FIG. 8B) for a gradientcopolymerization described in Example 20 below; and

FIGS. 9A-B are plots of molecular weight (M_(n)) and polydispersities(M_(w) /M_(n)) vs. time (FIG. 9A) and of the instantaneous compositionof the copolymer (F_(inst)) vs. chain length (FIG. 9B) for a gradientcopolymerization described in Example 20 below.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has been conceptualized that if (1) the organic halide R--M_(i) --Xresulting from an ATRA reaction is sufficiently reactive towards thetransition metal M_(t) ^(n) and (2) the alkene monomer is in excess, anumber or sequence of atom transfer radical additions (i.e., a possible"living"/ controlled radical polymerization) may occur. By analogy toATRA, the present new process of radical polymerization has been termed"atom (or group) transfer radical polymerization" (or "ATRP"), whichdescribes the involvement of (1) the atom or group transfer pathway and(2) a radical intermediate.

Living/controlled polymerization (i.e., when chain breaking reactionssuch as transfer and termination are substantially absent) enablescontrol of various parameters of macromolecular structure such asmolecular weight, molecular weight distribution and terminalfunctionalities. It also allows the preparation of various copolymers,including block and star copolymers. Living/controlled radicalpolymerization requires a low stationary concentration of radicals, inequilibrium with various dormant species.

In the context of the present invention, the term "controlled" refers tothe ability to produce a product having one or more properties which arereasonably close to their predicted value (presuming a particularinitiator efficiency). For example, if one assumes 100% initiatorefficiency, the molar ratio of catalyst to monomer leads to a particularpredicted molecular weight. The polymerization is said to be"controlled" if the resulting number average molecular weight (M_(w)(act)) is reasonably close to the predicted number average molecularweight (M_(w) (pred)); e.g., within an order of magnitude, preferablywithin a factor of four, more preferably within a factor of three andmost preferably within a factor of two (i.e., M_(w) (act) is in therange of from (0.1)×M_(w) (pred) to 10×M_(w) (pred), preferably from(0.25)×M_(w) (pred) to 4×M_(w) (pred), more preferably from (0.5)×M_(w)(pred) to 2 M_(w) (pred), and most preferably from (0.8)×M_(w) (pred) to1.2×M_(w) (pred)).

Similarly, one can "control" the polydispersity by ensuring that therate of deactivation is the same or greater than the initial rate ofpropagation. However, the importance of the relativedeactivation/propagation rates decreases proportionally with increasingpolymer chain length and/or increasing predicted molecular weight ordegree of polymerization.

The present invention describes use of novel initiating systems leadingto living/controlled radical polymerization. The initiation system isbased on the reversible formation of growing radicals in a redoxreaction between various transition metal compounds and an initiator,exemplified by (but not limited to) alkyl halides, aralkyl halides orhaloalkyl esters. Using 1-phenylethyl chloride (1-PECl) as a modelinitiator, CuCl as a model catalyst and bipyridine (Bpy) as a modelligand, a "living" radical bulk polymerization of styrene at 130° C.affords the predicted molecular weight up to M_(n) ≈10⁵ with a narrowmolecular weight distribution (e.g., M_(w) /M_(n) <1.5).

A key factor in the present invention is to achieve rapid exchangebetween growing radicals present at low stationary concentrations (inthe range of from 10⁻⁹ mol/L to 10⁻⁵ mol/L, preferably 10⁻⁸ mol/L to10⁻⁵ mol/L) and dormant chains present at higher concentrations(typically in the range 10⁻⁴ mol/L to 3 mol/L, preferably 10⁻² mol/L to10⁻¹ mol/L). It may be desirable to "match" theinitiator/catalyst/ligand system and monomer(s) such that theseconcentration ranges are achieved.

Although these concentration ranges are not essential to conductingpolymerization, certain disadvantageous effects may result if theconcentration ranges are exceeded. For example, if the concentration ofgrowing radicals exceeds 10₋₅ mol/L, there may be too many activespecies in the reaction, which may lead to an undesirable increase inthe rate of side reactions (e.g., radical-radical quenching, radicalabstraction from species other than the catalyst system, etc.). If theconcentration of growing radicals is less than 10⁻⁹ mol/L, the rate maybe undesirably slow. However, these considerations are based on anassumption that only free radicals are present in the reaction system.It is believed that some radicals are in a caged form, the reactivitiesof which, especially in termination-deactivation reactions, may differfrom those of uncaged free radicals.

Similarly, if the concentration of dormant chains is less than 10⁻⁴mol/L, the molecular weight of the product polymer may increasedramatically, thus leading to a potential loss of control of themolecular weight and the polydispersity of the product. On the otherhand, if the concentration of dormant species is greater than 3 mol/L,the molecular weight of the product may become too small, and theproperties of the product may more closely resemble the properties ofoligomers. (However, oligomeric products are useful, and are intended tobe included within the scope of the invention.)

For example, in bulk, a concentration of dormant chains of about 10⁻²mol/L provides product having a molecular weight of about 100,000 g/mol.On the other hand, a concentration of dormant chains exceeding 1M leadsto formation of (roughly) less than decameric products, and aconcentration of about 3M leads to formation of (predominantly) trimers.

In application Ser. No. 08/414,415 (incorporated herein by reference inits entirety), a method of preparing a (co)polymer by ATRP is disclosedwhich comprises:

polymerizing one or more radically polymerizable monomers in thepresence of an initiator having a radically transferable atom or group,a transition metal compound and a ligand to form a (co)polymer, thetransition metal compound being capable of participating in a redoxcycle with the initiator and a dormant polymer chain, and the ligandbeing any N-, O-, P- or S- containing compound which can coordinate in aσ-bond to the transition metal or any carbon-containing compound whichcan coordinate in a π-bond to the transition metal, such that directbonds between the transition metal and growing polymer radicals are notformed, and

isolating the formed (co)polymer.

The present invention includes the following:

(1) an ATRP process in which the improvement comprises polymerizing inthe presence of an amount of the corresponding reduced or oxidizedtransition metal compound which deactivates at least some free radicals;

(2) an ATRP process in which the improvement comprises polymerizing in ahomogeneous system or in the presence of a solubilizedinitiating/catalytic system;

(3) end-functional, site-specific functional and telechelic homopolymersand copolymers (see FIG. 1);

(4) block, random, graft, alternating and tapered (or "gradient")copolymers which may have certain properties or a certain structure(e.g., a copolymer of alternating donor and acceptor monomers, such asthe radical copolymer of isobutylene and a (meth)acrylate ester; seeFIG. 1);

(5) star, comb and dendritic (or "hyperbranched") polymers andcopolymers (see FIG. 1);

(6) end-functional and/or multi-functional hyperbranched polymers (seeFIG. 1);

(7) cross-linked polymers and gels;

(8) water-soluble polymers and new hydrogels (e.g., copolymers preparedby radical polymerization, comprising a water-soluble backbone andwell-defined hydrophobic (co)polymer chains grafted thereonto); and

(9) an ATRP process using water as a medium.

In one embodiment, the present invention concerns improved methods ofatom or group transfer radical polymerization, in which a proportion(e.g., 0.1-99.9 mol %, preferably 0.2-10 mol % and more preferably 0.5-5mol %) of the transition metal catalyst is in an oxidized or reducedstate, relative to the bulk of the transition metal catalyst. Theoxidized or reduced transition metal catalyst is the redox conjugate ofthe primary transition metal catalyst; i.e., for the M_(t) ^(n+) :M_(t)^(m+) redox cycle, 90-99.9 mol % of transition metal M_(t) atoms may bein the n⁺ oxidation state and 0.1-10 mol % of transition metal M_(t)atoms may be in the m⁺ oxidation state. The term "redox conjugate" thusrefers to the corresponding oxidized or reduced form of the transitionmetal catalyst. Oxidation states n and m are attained by transitionmetal M_(t) as a consequence of conducting ATRP.

The present Inventors have found that an amount of redox conjugatesufficient to deactivate at least some of the radicals which may form atthe beginning of polymerization (e.g., the product of self-initiation orof addition of an initiator radical or growing polymer chain radical toa monomer) greatly improves the polydispersity and control of themolecular weight of the product. The effects and importance of rates ofexchange between growing species of different reactivities and differentlifetimes, relative to the rate of propagation, has not beensufficiently explored in previous work by others, but has been found bythe present Inventors to have a tremendous effect on polydispersity andcontrol of molecular weight in living/controlled polymerizations.

As is shown in FIG. 2, both conventional and controlled polymerizationscomprise the reactions of initiating radicals with monomer at a rateconstant k_(i), propagation of growing chains with monomer at a rateconstant k_(p), and termination by coupling and/or disproportionationwith an average rate constant k_(t). In both systems, the concentrationof radicals at any given moment (the momentary concentration of growingradicals, or P!₀) is relatively low, about 10⁻⁷ mol/L or less.

However, in conventional radical polymerization, initiator is consumedvery slowly (k_(dec) ≈10⁻⁵ +1s⁻¹) . Furthermore, in conventional radicalpolymerization, the initiator half-lifetime is generally in the range ofhours, meaning that a significant proportion of initiator remainsunreacted, even after monomer is completely consumed.

By contrast, in controlled polymerization systems, the initiator islargely consumed at low monomer conversion (e.g., 90% or more ofinitiator may be consumed at less than 10% monomer conversion).

In ATRP, growing radicals are in dynamic equilibrium with dormantcovalent species. Covalent R--X and P--X bonds (initiator and dormantpolymer, respectively) are homolytically cleaved to form initiating (R⁻)or propagating (P⁻) radicals and corresponding counter-radicals X⁻. Theequilibrium position defines the momentary concentration of growingradicals, the polymerization rate and the contribution of termination.The dynamics of equilibration also affects polydispersity and themolecular weight of the polymer as a function of monomer conversion.

A model study has been performed on polymerization of methyl acrylate at100° C., based on numerical integration using a discrete Galerkin method(Predici program). In this study, the rate constants of propagation(k_(p) ═7×10³ mol⁻¹ L s⁻¹) and termination (k_(t) ═10⁷ mol¹ L s⁻¹) werebased on data available from published literature. The rate constants ofactivation and deactivation for the initiating system 1-phenylethylchloride/CuCl/2,2'-bipyridyl were then varied over five orders ofmagnitude, maintaining an equilibrium constant value K═10⁻⁸. As a resultof this model study, it was found that addition of 1% Cu(II) (redoxconjugate) dramatically improves the polydispersity of, and providespredictable molecular weights for, the obtained (co)polymer products.

The equilibrium constant (i.e., the ratio of the activation rateconstant k_(a) to deactivation rate constant k_(d)) can be estimatedfrom known concentrations of radicals, covalent alkyl halides, activatorand deactivator according to the equation:

    K═k.sub.a /k.sub.d ═( Cu.sup.II ! P.sup.- !)/( Cu.sup.I ! I!.sub.0)

Simulations were performed for bulk polymerization of methyl acrylate (M!₀ ═11 M) or styrene ( M!₀ ═9 M) using an initiating system containing1-PECl ( I!₀ ═0.1 M), a 2,2'-bipyridyl)CuCl complex ( Cu^(I) !0 ═0.1 M)and either 1% or 0% Cu^(II) as an initial deactivator ( Cu^(II!) ₀═0.001 M or 0 M). The stationary concentration of radicals isapproximately 10⁻⁷ M, leading to the result that K is approximately10⁻⁸.

After initiation in the system without Cu(II), the momentaryconcentration of radicals is reduced from 8×10⁻⁷ M at 10% conversion to3.3×10⁻⁷ M at 50% conversion and 1.6×10⁻⁷ M at 90% conversion. At thesame time, the concentration of deactivator (Cu^(II)) increases from1.2×10⁻⁴ M at 10% conversion to 3×10⁻⁴ M at 50% conversion and 6×10⁻⁴ Mat 90% conversion. The concentration of deactivator corresponds to theconcentration of terminated chains, which at 90% monomer conversion, isonly about 0.6% of all chains generated from the initiator.

In the presence of 1% deactivator (redox conjugate), a nearly constantconcentration of growing radicals is predicted. The momentaryconcentration of polymer radicals is much more constant in the presenceof 1% deactivator, going from 0.98×10⁻⁷ M at 10% conversion to 0.94×10⁻⁷M at 50% conversion and 0.86×10⁻⁷ M at 90% conversion. At the same time,the deactivator concentration increases from 1.01×10⁻³ M at 10%conversion to 1.05×10⁻³ M at 50% conversion and 1.15×10⁻³ M at 90%conversion. The concentration of terminated chains corresponds to theincrease in concentration of deactivator although the initialconcentration, which translates to 0.15% of all chains being terminatedat 90% conversion.

The dynamics of exchange has no effect on kinetics in the studied rangeof k_(a) and k_(d) values. However, dynamics has a tremendous effect onmolecular weights and polydispersities.

In the absence of deactivator in the model systems studied, a degree ofpolymerization (DP_(n)) of about 90 is expected. However, ifdeactivation is slow, very high molecular weights are initiallyobserved. As conversion increases, the molecular weights slowly begin tocoincide with predicted values. The initial discrepancy has a tremendouseffect on polydispersities, as will be discussed below.

If deactivation is sufficiently fast (in the model system, about 10⁷mol⁻¹ L s⁻¹), the predicted and observed molecular weights are insubstantial agreement from the beginning of polymerization. However,when deactivation is slow, the initial DP is substantially higher thanpredicted (DP═60 when k_(d) ═10⁻⁶ M⁻¹ s⁻¹, and DP═630 when k_(d) ═10⁻⁵M⁻¹ s⁻¹). Thus, initial values of DP can be predicted by the ratio ofpropagation to deactivation rates by the equation:

    DP═R.sub.p /R.sub.d ═k.sub.p  M!.sub.0  P.sup.- !/kd Cu.sup.II!.sub.0  P.sup.-!

Regardless of the rate of deactivation, however, initialpolydispersities are much higher than those predicted for a Poissondistribution. However, if deactivation is sufficiently fast, at completeconversion, vary narrow polydispersities (M_(w) /M_(n)) are observed(e.g., less than 1.1). On the other hand, if the rate of deactivation isabout the same as the rate of termination (in the model case, about 10⁷M⁻¹ s⁻¹), then the polydispersity at complete conversion is about 1.5.When deactivation is about three times slower, the polydispersity atcomplete conversion is about 2.5.

However, in the presence of 1% deactivator, a deactivation rate which isabout the same as the termination rate results in a polydispersity closeto ideal (<1.1) at complete conversion, although initially, it is ratherhigh (about 2), decreasing to about 1.5 at 25% conversion and <1.2 at75% conversion. Where deactivation is slower (k_(d) ═10⁶), the finalpolydispersity is 1.7. A small quantity of deactivator (redox conjugate)is sufficient to trap or quench the free radicals formed duringpolymerization. A large excess of redox conjugate is not necessary,although it does not have an adverse or continuous effect on thepolymerization rate.

It is noted that an average termination rate constant k_(t) ═10⁷ M⁻¹ s⁻¹was used. However, the actual termination rate constant strongly dependson chain length. For monomeric radicals, it can be as high at 10⁹ M⁻¹s⁻¹, but for very long chains, it can be as low as 10² M⁻¹ s⁻¹. Onemajor difference between controlled polymerization and conventionalradical polymerization is that nearly all chains have similar chainlength in controlled polymerization, whereas new radicals arecontinuously generated in conventional radical polymerization.Therefore, at substantial conversion, long chain radicals do not reactwith one another, but rather, with newly generated low molecular massradicals in conventional polymerization. In controlled systems, bycontrast, after a certain chain length has been achieved, the reactionmixture becomes more viscous, and the actual rate constant oftermination may dramatically drop, thus improving control ofpolymerization to a degree greater than one would predict prior to thepresent invention.

The addition of a redox conjugate to ATRP also increases control ofmolecular weight and polydispersities by scavenging radicals formed byother processes, such as thermal self-initiation of monomer. Forexample, in the model systems studied, CuCl₂ acts as an inhibitor ofpolymerization, and scavenges polymer chains at an early stage,preventing formation of a high molecular weight polymer which may beformed by thermal self-initiation.

It has been observed by the present Inventors that the rate ofpolymerization is not affected in a linear fashion by the amount orconcentration of the deactivating agent (redox conjugate). For example,the presence of 5 mol % of redox conjugate may be expected to decreasethe polymerization rate 10-fold relative to 0.5 mol % of redoxconjugate. However, 5 mol % of redox conjugate actually decreases thepolymerization rate by a significantly smaller amount than 10-foldrelative to 0.5 mol % of redox conjugate. Although a precise explanationfor this phenomenon is not yet available, it is believed that manyradicals generated by the present ATRP initiator/transition metalcompound/ligand system may be protected by a solvent/monomer "cage."Thus, the presence of more than 10 mol % of redox conjugate does notadversely affect polymerization by ATRP, although it may slow thepolymerization rate to a small extent.

Experimental observations also support the idea that large amounts ofredox conjugate are not harmful to polymerization, a result which issurprising in view of observations that redox conjugates adverselyaffect ATRA. For example, in the heterogeneous ATRP of acrylates usingcopper(I) chloride, the color of the catalyst changes from red (Cu^(I))to green (Cu^(II)). However, the apparent rate constant ofpolymerization is essentially constant, or at least does notsignificantly decrease.

As described above, the redox conjugate is present in an amountsufficient to deactivate at least some of the initially-formedinitiator-monomer adduct radicals, thermal self-initiation radicals andsubsequently-formed growing polymer radicals. One key to achievingnarrow polydispersities is to control the polymerization reactionparameters such that the rate of radical deactivation is roughly thesame as or greater than the rate of propagation.

In one embodiment, the improvement to the method comprises adding thetransition metal redox conjugate to the reaction mixture prior topolymerizing. Alternatively, when the transition metal compound iscommercially available as a mixture with its redox conjugate (e.g., manycommercially available Cu(I) salts contain 1-2 mol % of Cu(II)), theimproved process comprises adding the transition metal compound to thepolymerization reaction mixture without purification.

In an alternative embodiment, the improved ATRP method comprisesexposing the transition metal compound to oxygen for a length of timeprior to polymerizing the monomer(s). In preferred embodiments, thesource of oxygen is air, and the length of time is sufficient to providefrom 0.1 to 10 mol % of the redox conjugate of the transition metalcompound. This embodiment is particularly suitable when the transitionmetal is a Cu(I) compound, such as CuCl or CuBr.

One may also conduct a "reverse" ATRP, in which the transition metalcompound is in its oxidized state, and the polymerization is initiatedby, for example, a radical initiator such as azobis(isobutyronitrile)("AIBN"), a peroxide such as benzoyl peroxide (BPO) or a peroxy acidsuch as peroxyacetic acid or peroxybenzoic acid. The radical initiatoris believed to initiate "reverse" ATRP in the following fashion:##STR2## where "I" is the initiator, M_(t) ^(n) X_(n-1) is thetransition metal compound, M is the monomer, and I--M--X and M_(t) ^(n)X_(n-1) participate in "conventional" or "forward" ATRP in the mannerdescribed above.

After the polymerizing step is complete, the formed polymer is isolated.The isolating step of the present process is conducted by knownprocedures, and may comprise evaporating any residual monomer and/orsolvent, precipitating in a suitable solvent, filtering or centrifugingthe precipitated polymer, washing the polymer and drying the washedpolymer. Transition metal compounds may be removed by passing a mixturecontaining them through a column or pad of alumina, silica and/or clay.Alternatively, transition metal compounds may be oxidized (if necessary)and retained in the (co)polymer as a stabilizer.

Precipitation can be typically conducted using a suitable C₅ -C₈ -alkaneor C₅ -C₈ -cycloalkane solvent, such as pentane, hexane, heptane,cyclohexane or mineral spirits, or using a C₁ -C₆ -alcohol, such asmethanol, ethanol or isopropanol, or any mixture of suitable solvents.Preferably, the solvent for precipitating is water, hexane, mixtures ofhexanes, or methanol.

The precipitated (co)polymer can be filtered by gravity or by vacuumfiltration, in accordance with known methods (e.g., using a Buchnerfunnel and an aspirator). Alternatively, the precipitated (co)polymercan be centrifuged, and the supernatant liquid decanted to isolate the(co)polymer. The (co)polymer can then be can be washed with the solventused to precipitate the polymer, if desired. The steps of precipitatingand/or centrifuging, filtering and washing may be repeated, as desired.

Once isolated, the (co)polymer may be dried by drawing air through the(co)polymer, by vacuum, etc., in accordance with known methods(preferably by vacuum). The present (co)polymer may be analyzed and/orcharacterized by size exclusion chromatography, NMR spectroscopy, etc.,in accordance with known procedures.

The various initiating systems of the present invention work for anyradically polymerizable alkene, including (meth)acrylates, styrenes anddienes. It also provides various controlled copolymers, including block,random, alternating, gradient, star, graft or "comb," and hyperbranchedand/or dendritic (co)polymers. (In the present application,"(co)polymer" refers to a homopolymer, copolymer, or mixture thereof.)Similar systems have been used previously in organic synthesis, but havenot been used for the preparation of well-defined macromolecularcompounds.

In the present invention, any radically polymerizable alkene can serveas a monomer for polymerization. However, monomers suitable forpolymerization in the present method include those of the formula:##STR3## wherein R¹ and R² are independently selected from the groupconsisting of H, halogen, CN, straight or branched alkyl of from 1 to 20carbon atoms (preferably from 1 to 6 carbon atoms, more preferably from1 to 4 carbon atoms) which may be substituted with from 1 to (2n+1)halogen atoms where n is the number of carbon atoms of the alkyl group(e.g. CF₃), α, β-unsaturated straight or branched alkenyl or alkynyl of2 to 10 carbon atoms (preferably from 2 to 6 carbon atoms, morepreferably from 2 to 4 carbon atoms) which may be substituted with from1 to (2n-1) halogen atoms (preferably chlorine) where n is the number ofcarbon atoms of the alkyl group (e.g. CH₂ ═CCl--), C₃ -C₈ cycloalkylwhich may be substituted with from 1 to (2n-1) halogen atoms (preferablychlorine) where n is the number of carbon atoms of the cycloalkyl group,C(═Y)R⁵, C(═Y)NR⁶ R⁷, YC(═Y)R⁵, SOR⁵, SO₂ R⁵, OSO₂ R⁵, NR⁸ SO₂ R⁵, PR⁵₂, P(═Y)R⁵ ₂, YPR⁵ ₂, YP(═Y)R⁵ ₂, NR⁸ ₂ which may be quaternized with anadditional R⁸ group, aryl and heterocyclyl; where Y may be NR⁸, S or O(preferably O); R⁵ is alkyl of from 1 to 20 carbon atoms, alkylthio offrom 1 to 20 carbon atoms, OR²⁴ (where R²⁴ is H or an alkali metal),alkoxy of from 1 to 20 carbon atoms, aryloxy or heterocyclyloxy; R⁶ andR⁷ are independently H or alkyl of from 1 to 20 carbon atoms, or R⁶ andR⁷ may be joined together to form an alkylene group of from 2 to 7(preferably 2 to 5) carbon atoms, thus forming a 3- to 8-membered(preferably 3- to 6-membered) ring, and R⁸ is H, straight or branched C₁-C₂₀ alkyl or aryl;

R³ and R⁴ are independently selected from the group consisting of H,halogen (preferably fluorine or chlorine), C₁ -C₆ (preferably C₁) alkyland COOR⁹ (where R⁹ is H, an alkali metal, or a C₁ -C₆ alkyl group), or

R¹ and R³ may be joined to form a group of the formula (CH₂)_(n), (whichmay be substituted with from 1 to 2n' halogen atoms or C₁ -C₄ alkylgroups) or C(═O)--Y--C(═O), where n' is from 2 to 6 (preferably 3 or 4)and Y is as defined above; and

at least two of R¹, R², R³ and R⁴ are H or halogen.

In the context of the present application, the terms "alkyl", "alkenyl"and "alkynyl" refer to straight-chain or branched groups (except for C₁and C₂ groups). "Alkenyl" and "alkynyl" groups may have sites ofunsaturation at any adjacent carbon atom position(s) as long as thecarbon atoms remain tetravalent, but α,β- or terminal (i.e., at the ω-and (ω-1)-positions) are preferred.

Furthermore, in the present application, "aryl" refers to phenyl,naphthyl, phenanthryl, phenalenyl, anthracenyl, triphenylenyl,fluoranthenyl, pyrenyl, pentacenyl, chrysenyl, naphthacenyl, hexaphenyl,picenyl and perylenyl (preferably phenyl and naphthyl) in which eachhydrogen atom may be replaced with halogen, alkyl of from 1 to 20 carbonatoms (preferably from 1 to 6 carbon atoms and more preferably methyl)in which each of the hydrogen atoms may be independently replaced by anX group as defined above (e.g., a halide, preferably a chloride or abromide), alkenyl or alkynyl of from 2 to 20 carbon atoms in which eachof the hydrogen atoms may be independently replaced by an X group asdefined above (e.g., a halide, preferably a chloride or a bromide),alkoxy of from 1 to 6 carbon atoms, alkylthio of from 1 to 6 carbonatoms, C₃ -C₈ cycloalkyl in which each of the hydrogen atoms may beindependently replaced by an X group as defined above (e.g., a halide,preferably a chloride or a bromide), phenyl, NH₂ or C₁ -C₆ -alkylaminoor C₁ -C₆ -dialkylamino which may be quaternized with an R⁸ group, COR⁵,OC(═O)R⁵, SOR⁵, SO₂ R⁵, OSO₂ R⁵, PR⁵ ₂, POR⁵ ₂ and phenyl which may besubstituted with from 1 to 5 halogen atoms and/or C₁ -C₄ alkyl groups.(This definition of "aryl" also applies to the aryl groups in "aryloxy"and "aralkyl.") Thus, phenyl may be substituted from 1 to 5 times andnaphthyl may be substituted from 1 to 7 times (preferably, any arylgroup, if substituted, is substituted from 1 to 3 times) with one ormore of the above substituents. More preferably, "aryl" refers tophenyl, naphthyl, phenyl substituted from 1 to 5 times with fluorine orchlorine, and phenyl substituted from 1 to 3 times with a substituentselected from the group consisting of alkyl of from 1 to 6 carbon atoms,alkoxy of from 1 to 4 carbon atoms and phenyl. Most preferably, "aryl"refers to phenyl, tolyl, α-chlorotolyl, α-bromotolyl and methoxyphenyl.

In the context of the present invention, "heterocyclyl" refers topyridyl, furyl, pyrrolyl, thienyl, imidazolyl, pyrazolyl, pyrazinyl,pyrimidinyl, pyridazinyl, pyranyl, indolyl, isoindolyl, indazolyl,benzofuryl, isobenzofuryl, benzothienyl, isobenzothienyl, chromenyl,xanthenyl, purinyl, pteridinyl, quinolyl, isoquinolyl, phthalazinyl,quinazolinyl, quinoxalinyl, naphthyridinyl, phenoxathiinyl, carbazolyl,cinnolinyl, phenanthridinyl, acridinyl, 1,10-phenanthrolinyl,phenazinyl, phenoxazinyl, phenothiazinyl, oxazolyl, thiazolyl,isoxazolyl, isothiazolyl, and hydrogenated forms thereof known to thosein the art. Preferred heterocyclyl groups include pyridyl, furyl,pyrrolyl, thienyl, imidazolyl, pyrazolyl, pyrazinyl, pyrimidinyl,pyridazinyl, pyranyl and indolyl, the most preferred heterocyclyl groupbeing pyridyl. Accordingly, suitable vinyl heterocycles to be used as amonomer in the present invention include 2-vinyl pyridine, 4-vinylpyridine, 2-vinyl pyrrole, 3-vinyl pyrrole, 2-vinyl oxazole, 4-vinyloxazole, 2-vinyl thiazole, 4-vinyl thiazole, 2-vinyl imidazole, 4-vinylimidazole, 3-vinyl pyrazole, 4-vinyl pyrazole, 3-vinyl pyridazine,4-vinyl pyridazine, 3-vinyl isoxazole, 4-vinyl isoxazole, 3-vinylisothiazole, 4-vinyl isothiazole, 2-vinyl pyrimidine, 4-vinylpyrimidine, 5-vinyl pyrimidine, and 2-vinyl pyrazine, the most preferredbeing 2-vinyl pyridine. The vinyl heterocycles mentioned above may bearone or more substituents as defined above for an "aryl" group(preferably 1 or 2) in which each H atom may be independently replaced,e.g., with C₁ -C₆ alkyl groups, C₁ -C₆ alkoxy groups, cyano groups,ester groups or halogen atoms, either on the vinyl group or theheterocyclyl group, but preferably on the heterocyclyl group. Further,those vinyl heterocycles which, when unsubstituted, contain a N atom maybe quaternized with an R⁸ group (as defined above), and those whichcontain an N═H group may be protected at that position with aconventional blocking or protecting group, such as a C₁ -C₆ alkyl group,a tris-(C₁ -C₆ alkyl)silyl group, an acyl group of the formula R¹⁰ CO(where R¹⁰ is alkyl of from 1 to 20 carbon atoms in which each of thehydrogen atoms may be independently replaced by halide preferablyfluoride or chloride!), alkenyl of from 2 to 20 carbon atoms (preferablyvinyl), alkynyl of from 2 to 10 carbon atoms (preferably acetylenyl),phenyl which may be substituted with from 1 to 5 halogen atoms or alkylgroups of from 1 to 4 carbon atoms, or aralkyl (aryl-substituted alkyl,in which the aryl group is phenyl or substituted phenyl and the alkylgroup is from 1 to 6 carbon atoms, such as benzyl), etc. This definitionof "heterocyclyl" also applies to the heterocyclyl groups in"heterocyclyloxy" and "heterocyclic ring."

More specifically, preferred monomers include C₃ -C₁₂ α-olefins,isobutene, (meth)acrylic acid and alkali metal salts thereof,(meth)acrylate esters of C₁ -C₂₀ alcohols, acrylonitrile, acrylamide,cyanoacrylate esters of C₁ -C₂₀ alcohols, didehydromalonate diesters ofC₁ -C₆ alcohols, vinyl pyridines, vinyl N--C₁ --C₆ -alkylpyrroles,N-vinyl pyrrolidones, vinyl oxazoles, vinyl thiazoles, vinylpyrimidines, vinyl imidazoles, vinyl ketones in which the a-carbon atomof the alkyl group does not bear a hydrogen atom (e.g., vinyl C₁ -C₆-alkyl ketones in which both a-hydrogens are replaced with C₁ -C₄ alkyl,halogen, etc., or a vinyl phenyl ketone in which the phenyl may besubstituted with from 1 to 5 C₁ -C₆ -alkyl groups and/or halogen atoms),and styrenes which may bear a C₁ -C₆ -alkyl group on the vinyl moiety(preferably at the α-carbon atom) and from 1 to 5 (preferably from 1 to3) substituents on the phenyl ring selected from the group consisting ofC₁ -C₆ -alkyl, C₁ -C₆ -alkenyl (preferably vinyl), C₁ -C₆ -alkynyl(preferably acetylenyl), C₁ -C₆ -alkoxy, halogen, nitro, carboxy, C₁ -C₆-alkoxycarbonyl, hydroxy protected with a C₁ -C₆ acyl, SO₂ R⁵, cyano andphenyl. The most preferred monomers are isobutene, N-vinyl pyrrolidone,methyl acrylate (MA), methyl methacrylate (MMA), butyl acrylate (BA),2-ethylhexyl acrylate (EHA), acrylonitrile (AN), styrene (St) andp-tert-butylstyrene.

In the present invention, the initiator may be any compound having oneor more atom(s) or group(s) which are radically transferable under thepolymerizing conditions. Suitable initiators include those of theformula:

    R.sup.11 R.sup.12 R.sup.13 C--X

    R.sup.11 C(═O)--X

    R.sup.11 R.sup.12 R.sup.13 Si--X

    R.sup.11 R.sup.12 N--X

    R.sup.11 N--X.sub.2

    (R.sup.11).sub.n P(O).sub.m --X.sub.3-n

    (R.sup.11 O).sub.n P(O).sub.m --X.sub.3-n and

    (R.sup.11) (R.sup.12 O)P(O).sub.m --X

where:

X is selected from the group consisting of Cl, Br, I, OR¹⁰ (as definedabove), SR¹⁴, SeR¹⁴, OC(═O)R¹⁴, OP(═O)R¹⁴, OP(═O)(OR ¹⁴)₂, OP(═O)OR¹⁴,O--N(R¹⁴)₂, S--C(═S)N(R¹⁴)₂, CN, NC, SCN, CNS, OCN, CNO and N₃, whereR¹⁴ is aryl or a straight or branched C₁ -C₂₀ (preferably C₁ -Cl₁₀)alkyl group, or where an N(R¹⁴)₂ group is present, the two R¹⁴ groupsmay be joined to form a 5-, 6- or 7-membered heterocyclic ring (inaccordance with the definition of "heterocyclyl" above); and

R¹¹, R¹² and R¹³ are each independently selected from the groupconsisting of H, halogen, C₁ -C₂₀ alkyl (preferably C₁ -C₁₀ alkyl andmore preferably C₁ -C₆ alkyl), C₃ -C₈ cycloalkyl, R⁸ ₃ Si, C(═Y)R⁵,C(═Y)NR⁶ R⁷ (where R⁵ -R⁷ are as defined above), COCl, OH (preferablyonly one of R¹¹, R¹² and R¹³ is OH), CN, C₂ -C₂₀ alkenyl or alkynyl(preferably C₂ -C₆ alkenyl or alkynyl, and more preferably allyl orvinyl), oxiranyl, glycidyl, C₂ -C₆ alkylene or alkenylene substitutedwith oxiranyl or glycidyl, aryl, heterocyclyl, aralkyl, aralkenyl(aryl-substituted alkenyl, where aryl is as defined above, and alkenylis vinyl which may be substituted with one or two C₁ -C₆ alkyl groupsand/or halogen atoms preferably chlorine!), C₁ -C₆ alkyl in which from 1to all of the hydrogen atoms (preferably 1) are replaced with halogen(preferably fluorine or chlorine where 1 or more hydrogen atoms arereplaced, and preferably fluorine, chlorine or bromine where 1 hydrogenatom is replaced) and C₁ -C₆ alkyl substituted with from 1 to 3substituents (preferably 1) selected from the group consisting of C₁ -C₄alkoxy, aryl, heterocyclyl, C(═Y)R⁵ (where R⁵ is as defined above),C(═Y)NR⁶ R⁷ (where R⁶ and R⁷ are as defined above), oxiranyl andglycidyl; preferably such that no more than two of R¹¹, R¹² and R¹³ areH (more preferably no more than one of R¹¹, R¹² and R¹³ is H);

m is 0 or 1; and

n is 0, 1 or 2.

In the present invention, X is preferably Cl or Br. Cl-containinginitiators generally provide (1) a slower reaction rate and (2) higherproduct polydispersity than the corresponding Br-containing initiators.However, Cl-terminated polymers generally have higher thermal stabilitythan the corresponding Br-terminated polymers.

When an alkyl, cycloalkyl, or alkyl-substituted aryl group is selectedfor one of R¹¹, R¹² and R¹³, the alkyl group may be further substitutedwith an X group as defined above. Thus, it is possible for the initiatorto serve as a starting molecule for branch or star (co)polymers. Oneexample of such an initiator is a 2,2-bis(halomethyl)-1,3-dihalopropane(e.g., 2,2-bis(chloromethyl)-1,3-dichloropropane,2,2-bis(bromomethyl)-1,3-dibromopropane), and a preferred example iswhere one of R¹¹, R¹² and R¹³ is phenyl substituted with from one tofive C₁ -C₆ alkyl substituents, each of which may independently befurther substituted with a X group (e.g., α,α'-dibromoxylene, tetrakis-or hexakis(α-chloro- or α-bromomethyl)-benzene).

Preferred initiators include 1-phenylethyl chloride and 1-phenylethylbromide (e.g., where R¹¹ ═Ph, R¹² ═CH₃, R¹³ ═H and X═Cl or Br),chloroform, carbon tetrachloride, 2-chloropropionitrile, C₁ -C₆ -alkylesters of a 2-halo-C₁ -C₆ -carboxylic acid (such as 2-chloropropionicacid, 2-bromopropionic acid, 2-chloroisobutyric acid, 2-bromoisobutyricacid, etc.), p-halomethylstyrenes and compounds of the formula C₆ H_(x)(CH₂ X)_(y) or CX_(x') (CH₂)_(n) (CH₂ X)!y', where X is Cl or Br, x+y=6,x'+y'=4, 0≦n≦5 and both y' and y≧1. More preferred initiators include1-phenylethyl chloride, 1-phenylethyl bromide, methyl2-chloropropionate, ethyl 2-chloropropionate, methyl 2-bromopropionate,ethyl 2-bromoisobutyrate, p-chloromethylstyrene, α,α'-dichloroxylene,α,α'-dibromoxylene and hexakis(a-bromomethyl)benzene.

Any transition metal compound which can participate in a redox cyclewith the initiator and dormant polymer chain is suitable for use in thepresent invention. Preferred transition metal compounds are those whichdo not form a direct carbon-metal bond with the polymer chain.Particularly suitable transition metal compounds are those of theformula M_(t) ^(n+) X'_(n), where:

M_(t) ^(n+) may be, for example, selected from the group consisting ofCu¹⁺, Cu²⁺, Au⁺, Au²⁺, Au³⁺, Ag⁺, Ag²⁺, Hg⁺, Hg²⁺, Ni⁰, Ni⁺, Ni²⁺, Ni³⁺,Pd⁰, Pd⁺, Pd²⁺, Pt⁰, Pt⁺, Pt⁺², Pt⁺³, Pt⁺⁴, Rh⁺, Rh²⁺, Rh³⁺, Rh⁴⁺, Co⁺,Co²⁺, Co³⁺, Ir⁰, Ir⁺, Ir²⁺, Ir³⁺, Ir⁴⁺, Fe²⁺, Fe³⁺, Ru²⁺, Ru³⁺, Ru⁴⁺,Ru⁵⁺, Ru⁶⁺, Os²⁺, Os³⁺, Os⁴⁺, Re²⁺, Re³⁺, Re⁴⁺, Re⁶⁺, Re⁷⁺, Mn²⁺, Mn³⁺,Mn⁴⁺, Cr²⁺, Cr³⁺, Mo⁰, Mo⁺, Mo²⁺, Mo³⁺, W²⁺, W³⁺, V²⁺, V³⁺, V⁴⁺, V⁵⁺,Nb²⁺, Nb⁺³, Nb⁴⁺, Nb⁵⁺, Ta³⁺, Ta⁴⁺, Ta⁵⁺, Zn⁺ and Zn²⁺ ;

X' may be, for example, selected from the group consisting of halogen,OH, (O)_(1/2), C₁ -C₆ -alkoxy, (SO₄)_(1/2), (PO₄)_(1/3), (HPO₄)_(1/2),(H₂ PO₄), triflate, hexafluorophosphate, methanesulfonate, arylsulfonate(preferably benzenesulfonate or toluenesulfonate), SeR¹⁴, CN, NC, SCN,CNS, OCN, CNO, N₃ and R¹⁵ CO₂, where R¹⁴ is as defined above and R¹⁵ isH or a straight or branched C₁ -C₆ alkyl group (preferably methyl) oraryl (preferably phenyl) which may be substituted from 1 to 5 times witha halogen (preferably 1 to 3 times with fluorine or chlorine); and

n is the formal charge on the metal (e.g., 0≦n≦7).

Suitable ligands for use in the present invention include compoundshaving one or more nitrogen, oxygen, phosphorus and/or sulfur atomswhich can coordinate to the transition metal through a σ-bond, ligandscontaining two or more carbon atoms which can coordinate to thetransition metal through a π-bond, ligands having a carbon atom whichcan coordinate to the transition metal through a σ-bond but which do notform a carbon-carbon bond with the monomer under the conditions of thepolymerizing step (e.g., ligands which do not participate in β-additionreactions with (coordinated) monomers; see, e.g., the ligand(s)described by van de Kuil et al, supra; and van Koten et al, Recl. Trav.Chim. Pays-Bas, 113, 267-277 (1994)), and ligands which can coordinateto the transition metal through a μ-bond or a η-bond.

Preferred N-, O-, P- and S- containing ligands may have one of thefollowing formulas:

    R.sup.16 --Z--R.sup.17 or

    R.sup.16 --Z--(R.sup.18 --Z).sub.m --R.sup.17

where:

R¹⁶ and R¹⁷ are independently selected from the group consisting of H,C₁ -C₂₀ alkyl, aryl, heterocyclyl, and C₁ -C₆ alkyl substituted with C₁-C₆ alkoxy, C₁ -C₄ dialkylamino, C(═Y)R⁵, C(═Y)R⁶ R⁷ and/or YC(═Y)RB,where Y, R⁵, R⁶, R⁷ and R⁸ are as defined above; or

R¹⁶ and R¹⁷ can be joined to form a saturated, unsaturated orheterocyclic ring as described above for the "heterocyclyl" group;

Z is O, S, NR¹⁹ or PR¹⁹, where R¹⁹ is selected from the same group asR¹⁶ and R¹⁷,

each R¹⁸ is independently a divalent group selected from the groupconsisting of C₂ -C₄ alkylene (alkanediyl) and C₂ -C₄ alkenylene wherethe covalent bonds to each Z are at vicinal positions (e.g., in a1,2-arrangement) or at β-positions (e.g., in a 1,3-arrangement) and C₃-C₈ cycloalkanediyl, C₃ -C₈ cycloalkenediyl, arenediyl andheterocyclylene where the covalent bonds to each Z are at vicinalpositions; and

m is from 1 to 6.

In addition to the above ligands, each of R¹⁶ --Z and R¹⁷ --Z can form aring with the R¹⁸ group to which the Z is bound to form a linked orfused heterocyclic ring system (such as is described above for"heterocyclyl"). Alternatively, when R¹⁶ and/or R¹⁷ are heterocyclyl, Zcan be a covalent bond (which may be single or double), CH₂ or a 4- to7-membered ring fused to R¹⁶ and/or R¹⁷, in addition to the definitionsgiven above for Z. Exemplary ring systems for the present ligand includebipyridyl, bipyrrole, 1,10-phenanthroline, a cryptand, a crown ether,etc.

Where Z is PR¹⁹, R¹⁹ can also be C₁ -C₂₀ -alkoxy.

Also included as suitable ligands in the present invention are CO(carbon monoxide), porphyrins and porphycenes, the latter two of whichmay be substituted with from 1 to 6 (preferably from 1 to 4) halogenatoms, C₁ -C₆ alkyl groups, C₁ -C₆ -alkoxy groups, C₁ -C₆alkoxycarbonyl, aryl groups, heterocyclyl groups, and C₁ -C₆ alkylgroups further substituted with from 1 to 3 halogens.

Further ligands suitable for use in the present invention includecompounds of the formula R²⁰ R²¹ C(C(═Y)R⁵)₂, where Y and R⁵ are asdefined above, and each of R²⁰ and R²¹ is independently selected fromthe group consisting of H, halogen, C₁ -C₂₀ alkyl, aryl andheterocyclyl, and R²⁰ and R²¹ may be joined to form a C₃ -C₈ cycloalkylring or a hydrogenated (i.e., reduced, non-aromatic or partially orfully saturated) aromatic or heterocyclic ring (consistent with thedefinitions of "aryl" and "heterocyclyl" above), any of which (exceptfor H and halogen) may be further substituted with 1 to 5 and preferably1 to 3 C₁ -C₆ alkyl groups, C₁ -C₆ alkoxy groups, halogen atoms and/oraryl groups. Preferably, one of R²⁰ and R²¹ is H or a negative charge.

Additional suitable ligands include, for example, ethylenediamine andpropylenediamine, both of which may be substituted from one to fourtimes on the amino nitrogen atom with a C₁ -C₄ alkyl group or acarboxymethyl group; aminoethanol and aminopropanol, both of which maybe substituted from one to three times on the oxygen and/or nitrogenatom with a C₁ -C₄ alkyl group; ethylene glycol and propylene glycol,both of which may be substituted one or two times on the oxygen atomswith a C₁ -C₄ alkyl group; diglyme, triglyme, tetraglyme, etc.

Suitable carbon-based ligands include arenes (as described above for the"aryl" group) and the cyclopentadienyl ligand. Preferred carbon-basedligands include benzene (which may be substituted with from one to sixC₁ -C₄ alkyl groups e.g., methyl!) and cyclopentadienyl (which may besubstituted with from one to five methyl groups, or which may be linkedthrough an ethylene or propylene chain to a second cyclopentadienylligand). Where the cyclopentadienyl ligand is used, it may not benecessary to include a counteranion (X') in the transition metalcompound.

Preferred ligands include unsubstituted and substituted pyridines andbipyridines (where the substituted pyridines and bipyridines are asdescribed above for "heterocyclyl"), acetonitrile, (R¹⁰ O)₃ P, PR¹⁰ ₃,1,10-phenanthroline, porphyrin, cryptands such as K₂₂₂ and crown etherssuch as 18-crown-6. The most preferred ligands are bipyridyl,4,4'-dialkyl-bipyridyls and (R¹⁰ O)₃ P.

A preformed transition metal-ligand complex can be used in place of amixture of transition metal compound and ligand without affecting thebehavior of the polymerization.

The present invention also concerns an improved atom or group transferradical polymerization process employing a solubilized catalyst, whichin a preferred embodiment, results in a homogeneous polymerizationsystem. In this embodiment, the method employs a ligand havingsubstituents rendering the transition metal-ligand complex at leastpartially soluble, preferably more soluble than the correspondingcomplex in which the ligand does not contain the substituents, and morepreferably, at least 90 to 99% soluble in the reaction medium.

In this embodiment, the ligand may have one of the formulas R¹⁶--Z--R¹⁷, R¹⁶ --Z--(R¹⁸ --Z)_(m) --R¹⁷ or R²⁰ R²¹ C(C(═Y)R⁵)₂ above,where at least one of R¹⁶ and R¹⁷ or at least one of R²⁰ and R²¹ are C₂-C₂₀ alkyl, C₁ -C₆ alkyl substituted with C₁ -C₆ alkoxy and/or C₁ -C₄dialkylamino, or are aryl or heterocyclyl substituted with at least onealiphatic substituent selected from the group consisting of C₁ -C₂₀alkyl, C₂ -C₂₀ alkylene, c₂ -C₂₀ alkynylene and aryl such that at leasttwo, preferably at least four, more preferably at least six, and mostpreferably at least eight carbon atoms are members of the aliphaticsubstituent(s). Particularly preferred ligands for this embodiment ofthe invention include 2,2'-bipyridyl having at least two alkylsubstituents containing a total of at least eight carbon atoms, such as4,4'-di-(5-nonyl)-2,2'-bipyridyl (dNbipy),4,4'-di-n-heptyl-2,2'-bipyridyl (dHbipy) and4,4'-di-tert-butyl-2,2'-bipyridyl (dTbipy).

Particularly when combined with the aforementioned process forpolymerizing a monomer in the presence of a small amount of transitionmetal redox conjugate, a substantial improvement in productpolydispersity is observed. Whereas heterogeneous ATRP yields polymerswith polydispersities generally ranging from 1.1 to 1.5, so-called"homogeneous ATRP" (e.g., based on dNbipy, dHbipy or dtbipy) withtransition metal redox conjugate present (e.g., Cu(I)/Cu(II)) yieldspolymers with polydispersities ranging from less than 1.05 to 1.10.

In the present polymerization, the amounts and relative proportions ofinitiator, transition metal compound and ligand are those effective toconduct ATRP. Initiator efficiencies with the presentinitiator/transition metal compound/ligand system are generally verygood (e.g., at least 25%, preferably at least 50%, more preferably >80%,and most preferably >90%). Accordingly, the amount of initiator can beselected such that the initiator concentration is from 10⁻⁴ M to 3M,preferably 10⁻³ -10⁻¹ M. Alternatively, the initiator can be present ina molar ratio of from 10^(-4:1) to 0.5:1, preferably from 10^(-3:1) to5×10^(-2:1), relative to monomer. An initiator concentration of 0.1-1Mis particularly useful for preparing end-functional polymers.

The molar proportion of transition metal compound relative to initiatoris generally that which is effective to polymerize the selectedmonomer(s), but may be from 0.0001:1 to 10:1, preferably from 0.1:1 to5:1, more preferably from 0.3:1 to 2:1, and most preferably from 0.9:1to 1.1:1. Conducting the polymerization in a homogeneous system maypermit reducing the concentration of transition metal and ligand suchthat the molar proportion of transition metal compound to initiator isas low as 0.001:1.

Similarly, the molar proportion of ligand relative to transition metalcompound is generally that which is effective to polymerize the selectedmonomer(s), but can depend upon the number of coordination sites on thetransition metal compound which the selected ligand will occupy. (One ofordinary skill understands the number of coordination sites on a giventransition metal compound which a selected ligand will occupy.) Theamount of ligand may be selected such that the ratio of (a) coordinationsites on the transition metal compound to (b) coordination sites whichthe ligand will occupy is from 0.1:1 to 100:1, preferably from 0.2:1 to10:1, more preferably from 0.5:1 to 3:1, and most preferably from 0.8:1to 2:1. However, as is also known in the art, it is possible for asolvent or for a monomer to act as a ligand. For the purposes of thisapplication, however, the monomer is preferably (a) distinct from and(b) not included within the scope of the ligand, although in someembodiments (e.g., the present process for preparing a graft and/orhyperbranched (co)polymer), the monomer may be self-initiating (i.e.,capable of serving as both initiator and monomer). Nonetheless, certainmonomers, such as acrylonitrile, certain (meth)acrylates and styrene,are capable of serving as ligands in the present invention, independentof or in addition to their use as a monomer.

The present polymerization may be conducted in the absence of solvent("bulk" polymerization). However, when a solvent is used, suitablesolvents include ethers, cyclic ethers, C₅ -C₁₀ alkanes, C₅ -C₈cycloalkanes which may be substituted with from 1 to 3 C₁ -C₄ alkylgroups, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents,acetonitrile, dimethylformamide, ethylene carbonate, propylenecarbonate, dimethylsulfoxide, dimethylsulfone, water, mixtures of suchsolvents, and supercritical solvents (such as CO₂, C₁ -C₄ alkanes inwhich any H may be replaced with F, etc.). The present polymerizationmay also be conducted in accordance with known suspension, emulsion,miniemulsion, gas phase, dispersion, precipitation and reactiveinjection molding polymerization processes, particularly mimiemulsionand dispersion polymerization processes.

Suitable ethers include compounds of the formula R²² OR²³, in which eachof R²² and R²³ is independently an alkyl group of from 1 to 6 carbonatoms or an aryl group (such as phenyl) which may be further substitutedwith a C₁ -C₄ -alkyl or C₁ -C₄ -alkoxy group. Preferably, when one ofR²² and R²³ is methyl, the other of R²² and R²³ is alkyl of from 4 to 6carbon atoms, C₁ -C₄ -alkoxyethyl or p-methoxyphenyl. Examples includediethyl ether, ethyl propyl ether, dipropyl ether, methyl t-butyl ether,di-t-butyl ether, glyme (dimethoxyethane), diglyme (diethylene glycoldimethyl ether), 1,4-dimethoxybenzene, etc.

Suitable cyclic ethers include THF and dioxane. Suitable aromatichydrocarbon solvents include benzene, toluene, o-xylene, m-xylene,p-xylene and mixtures thereof. Suitable halogenated hydrocarbon solventsinclude CH₂ Cl₂, 1,2-dichloroethane and benzene substituted from 1 to 6times with fluorine and/or chlorine, although preferably, the selectedhalogenated hydrocarbon solvent(s) does not act as an initiator underthe polymerization reaction conditions.

ATRP may also be conducted either in bulk or in an aqueous medium toprepare water-soluble or water-miscible polymers. Water-soluble polymersare important scientifically and commercially, because they find a widerange of applications in mineral-processing, water-treatment, oilrecovery, etc. (Bekturov, E. A.; Bakauova, Z. K. Synthetic Water-SolublePolymers in Solution, Huethig and Wepf: Basel, 1986; Molyneux, P.Water-Soluble Synthetic Polymers: Properties and Behavior, CRC Press:Boca Raton, Fla., 1991). Many of the industrially importantwater-soluble polymers are prepared by the free-radical polymerizationof acrylic and vinyl monomers, because this polymerization technique isamenable for use in aqueous solutions (Elias, H.; Vohwinkel, F. NewCommercial Polymers 2; Gordon and Breach: New York, 1986). For thesereasons, it is beneficial to develop well-controlled radicalpolymerizations for use in aqueous polymerizations (Keoshkerian, B.;Georges, M. K.; Boils-Boissier, D. Macromolecules 1995, 28, 6381).

Thus, the present ATRP process can be conducted in an aqueous medium. An"aqueous medium" refers to a water-containing mixture which is liquid atreaction and processing temperatures. Examples include water, eitheralone or admixed with a water-soluble C₁ -C₄ alcohol, ethylene glycol,glycerol, acetone, methyl ethyl ketone, dimethylformamide,dimethylsulfoxide, dimethylsulfone, hexamethylphosphoric triamide, or amixture thereof. Additionally, the pH of the aqueous medium may beadjusted to a desired value with a suitable mineral acid or base (e.g.,phosphoric acid, hydrochloric acid, ammonium hydroxide, NaOH, NaHCO₃,Na₂ CO₃, etc.). However, the preferred aqueous medium is water.

When conducted in an aqueous medium, the polymerization temperature maybe from 0° C. to the reflux temperature of the medium, preferably from20° C. to 100° C. and more preferably from 70° C. to 100° C. Preferably,the monomer(s) polymerized in this embodiment are at least partiallywater-soluble or water-miscible, or alternatively, capable of beingpolymerized in an aqueous emulsion which further comprises a surfactant(preferably in an amount sufficient to emulsify the monomer(s). Suchmonomers are preferably sufficiently soluble in 80° C. water to providea monomer concentration of at least 10⁻² M, and more preferably 10⁻¹ M.

Suitable water-soluble or water-miscible monomers include those of theformula: ##STR4## wherein R¹ and R² are independently selected from thegroup consisting of H, halogen, CN, straight or branched alkyl of from 1to 10 carbon atoms (preferably from 1 to 6 carbon atoms, more preferablyfrom 1 to 4 carbon atoms) which may be substituted, α,β-unsaturatedstraight or branched alkenyl or alkynyl of 2 to 10 carbon atoms(preferably from 2 to 6 carbon atoms, more preferably from 2 to 4 carbonatoms) which may be substituted, C₃ -C₈ cycloalkyl which may besubstituted, NR⁸ ₂, N⁺ R⁸ ₃, C(═Y)R⁵, C(═Y)NR⁶ R⁷, YC(═Y)R⁸, YC(═Y)YR⁸,YS(═Y)R⁸, YS (═Y)₂ R⁸, YS (═Y)₂ YR⁸, P(R⁸)₂, P (═Y) (R⁸)₂ , P (YR⁸)₂, P(═Y) (YR⁸)₂ , P(YR⁸)R⁸, P(═Y) (YR⁸)R⁸, and aryl or heterocyclyl (asdefined above) in which one or more nitrogen atoms (if present) may bequaternized with an R⁸ group (preferably H or C₁ -C₄ alkyl); where Y maybe NR⁸, S or O (preferably O), R⁵ is alkyl of from 1 to 10 carbon atoms,alkoxy of from 1 to 10 carbon atoms, aryl, aryloxy or heterocyclyloxy;R⁶ and R⁷ are independently H or alkyl of from 1 to 20 carbon atoms, orR⁶ and R⁷ may be joined together to form an alkylene group of from 2 to5 carbon atoms, thus forming a 3- to 6-membered ring; and R⁸ is(independently) H, straight or branched C₁ -C₁₀ alkyl (which may bejoined to form a 3- to 8-membered ring where more than one R⁸ group iscovalently bound to the same atom) or aryl, and when R⁸ is directlybonded to S or O, it may be an alkali metal or an ammonium (N⁺ R⁸ ₄)group; and

R³ and R⁴ are independently selected from the group consisting of H,halogen (preferably fluorine or chlorine), CN, C₁ -C₆ (preferably C₁)alkyl and COOR⁹ (where R⁹ is as defined above); or

R¹ and R³ may be joined to form a group of the formula (CH₂)_(n') (whichmay be substituted) or C(═O)--Y--C(═O), where n' is from 2 to 6(preferably 3 or 4) and Y is as defined above;

at least two of R¹, R², R³ and R⁴ are H or halogen; and at least one ofR¹, R², R³ and R⁴ in at least one monomer is, or is substituted with,OH, NR⁸ ₂, N⁺ R⁸ ₃, COOR⁹, C(═Y)R⁵, C(═Y)NR⁶ R⁷, YC(═Y)R⁸, YC(═Y)YR⁸,YS(═Y)R⁸, YS(═Y)₂ R⁸, YS(═Y)₂ YR⁸, P(YR⁸)₂, P(═Y) (YR⁸)₂, P(YR⁸)R⁸,P(═Y) (YR⁸)R⁸, P(═Y)R⁸ ₂, hydroxy-substituted C₁ -C₁₀ alkyl orhetercyclyl in which one or more nitrogen atoms is quaternized with anR⁸ group (e.g., H or C₁ -C₄ alkyl).

A group "which may be substituted" refers to the alkyl, alkenyl,alkynyl, aryl, heterocyclyl, alkylene and cycloalkyl groups substitutedin accordance with the descriptions herein. A preferred monomer is asulfonated acrylamide.

The present invention also encompasses water swellable polymers andhydrogels. Hydrogels are polymers which, in the presence of water, donot dissolve, but absorb water and thus swell in size. These polymershave found wide applications ranging from drug delivery to oil recovery.Generally, these polymeric materials are synthesized by radicalpolymerization of a water-soluble material in the presence of a divinylmonomer. The divinyl monomer introduces chemical cross links which makesthe polymer permanently insoluble in any solvent (i.e., withoutdegrading the polymer and its physical properties).

The present ATRP process also provides a process for synthesizing ahydrogel which utilizes physical cross links between chains and whichallows for dissolution of the polymer without loss of physicalproperties. The present water swellable polymers and hydrogel polymerscan also be processed from a melt, a characteristic that polymers havingchemical crosslinks lack. The water-soluble monomers described above maybe used to prepare the present water swellable (co)polymers andhydrogels. An exemplary polymer which was synthesized to demonstratesuch abilities is poly(N-vinylpyrrolidinone-g-styrene) (see the Examplesbelow).

In a preferred embodiment, the hydrogel comprises a base (co)polymer andat least two (preferably at least three, more preferably at least four,and even more preferably at least five) relatively hydrophobicside-chains grafted thereonto (e.g., by conventional radicalpolymerization or by the present ATRP process). The base (co)polymer maybe a (co)polymer containing a water-soluble or water-miscible monomer inan amount sufficient to render the (co)polymer water-soluble orwater-miscible (e.g., containing at least 10 mol. %, preferably at least30 mol. %, and preferably at least 50 mol. % of the water-soluble orwater-miscible monomer). Preferred hydrophobic side-chains containmonomeric units of the formula --R¹ R² C--CR³ R⁴ --, in which:

R¹ and R² are independently selected from the group consisting of H,halogen, CN, straight or branched alkyl of from 1 to 10 carbon atoms(preferably from 1 to 6 carbon atoms, more preferably from 1 to 4 carbonatoms) which may be substituted, straight or branched alkenyl or alkynylof from 2 to 10 carbon atoms (preferably from 2 to 6 carbon atoms, morepreferably from 2 to 3 carbon atoms) which may be substituted, C₃ -C₈cycloalkyl which may be substituted, NR⁸ ₂, C(═Y)R⁵, C(═Y) NR⁶ R⁷,YC(═Y) R⁸, YC(═Y)YR⁸, YS(═Y)R⁸, YS(═Y) ₂ R⁸, YS(═Y)₂ YR⁸, P(R⁸)₂, P(═Y)(R⁸)₂, P(YR⁸)₂, P(═Y) (YR⁸)₂, P(YR⁸)R⁸, P(═Y) (YR⁸)R⁸, and aryl orheterocyclyl in which each H atom may be replaced with halogen atoms,NR⁸ ₂, C₁ -C₆ alkyl or C₁ -C₆ alkoxy groups; where Y may be NR⁸, S or O(preferably O); R⁵ is alkyl of from 1 to 10 carbon atoms, alkoxy of from1 to 10 carbon atoms, aryl, aryloxy or heterocyclyloxy; R⁶ and R⁷ arealkyl of from 1 to 20 carbon atoms, or R⁶ and R⁷ may be joined togetherto form an alkylene group of from 2 to 7 carbon atoms, thus forming a 3-to 8-membered ring; and R⁸ is (independently) straight or branched C₁-C₁₀ alkyl (which may be joined to form a 3- to 7-membered ring wheremore than one R⁸ group is covalently bound to the same atom); and

R³ and R⁴ are independently selected from the group consisting of H,halogen (preferably fluorine or chlorine), CN, C₁ -C₆ (preferably C₁)alkyl and COOR⁹ (where R⁹ is alkyl of from 1 to 10 carbon atoms oraryl);

R¹ and R³ may be joined to form a group of the formula (CH₂)_(n) '(which may be substituted) where n' is from 2 to 6 (preferably 3 or 4);and

at least two of R¹, R², R³ and R⁴ are H or halogen.

Polymers produced by the present process may be useful in general asmolding materials (e.g., polystyrene containers) and as barrier orsurface materials (e.g., poly(methyl methacrylate), or PMMA, iswell-known in this regard as PLEXIGLAS™). However, the polymers producedby the present process, which typically will have uniform, predictable,controllable and/or tunable properties relative to polymers produced byconventional radical polymerization, will be most suitable for use inspecialized or performance applications.

For example, block copolymers of polystyrene and polyacrylate (e.g.,PSt-PA-PSt triblock copolymers) are useful thermoplastic elastomers.Poly(methyl methacrylate)-polyacrylate triblock copolymers (e.g.,PMMA-PA-PMMA) are useful, fully acrylic thermoplastic elastomers. Homo-and copolymers of styrene, (meth)acrylates and/or acrylonitrile areuseful plastics, elastomers and adhesives. Either block or randomcopolymers of styrene and a (meth)acrylate or acrylonitrile may beuseful thermoplastic elastomers having high solvent resistance.

Furthermore, block copolymers in which the blocks alternate betweenpolar monomers and non-polar monomers produced by the present inventionare useful amphiphilic surfactants or dispersants for making highlyuniform polymer blends. Star polymers produced by the present processare useful high-impact (co)polymers. (For example, STYROLUX™, ananionically-polymerized styrene-butadiene star block copolymer, is aknown, useful high-impact copolymer.)

The (co)polymers of the present invention (and/or a block thereof) mayhave an average degree of polymerization (DP) of at least 3, preferablyat least 5, and more preferably at least 10, and may have a weightand/or number average molecular weight of at least 250 g/mol, preferablyat least 500 g/mol, more preferably at least 1,000 g/mol, even morepreferably at least 2,000 g/mol, and most preferably at least 3,000g/mol. The present (co)polymers, due to their "living" character, canhave a maximum molecular weight without limit. However, from a practicalperspective, the present (co)polymers and blocks thereof may have anupper weight or number average molecular weight of, e.g., 5,000,000g/mol, preferably 1,000,000 g/mol, more preferably 500,000 g/mol, andeven more preferably 250,000 g/mol. For example, when produced in bulk,the number average molecular weight may be up to 1,000,000 (with aminimum weight or number average molecular weight as mentioned above).

The number average molecular weight may be determined by size exclusionchromatography (SEC) or, when the initiator has a group which can beeasily distinguished from the monomer(s), by NMR spectroscopy (e.g.,when 1-phenylethyl chloride is the initiator and methyl acrylate is themonomer).

Thus, the present invention also encompasses novel end-functional,telechelic and hyperbranched homopolymers, and block, multi-block, star,gradient, random, graft or "comb" and hyperbranched copolymers. Each ofthe these different types of copolymers will be described hereunder.

Because ATRP is a "living" polymerization, it can be started andstopped, practically at will. Further, the polymer product retains thefunctional group "X" necessary to initiate a further polymerization.Thus, in one embodiment, once the first monomer is consumed in theinitial polymerizing step, a second monomer can then be added to form asecond block on the growing polymer chain in a second polymerizing step.Additional polymerizations with the same or different monomer(s) can beperformed to prepare multi-block copolymers.

Furthermore, since ATRP is radical polymerization, blocks can beprepared in essentially any order. One is not necessarily limited topreparing block copolymers where the sequential polymerizing steps mustflow from the least stabilized polymer intermediate to the moststabilized polymer intermediate, such as is necessary in ionicpolymerization. Thus, one can prepare a multi-block copolymer in which apolyacrylonitrile or a poly(meth)acrylate block is prepared first, thena styrene or butadiene block is attached thereto, etc.

As is described throughout the application, certain advantageousreaction design choices will become apparent. However, one is notlimited to those advantageous reaction design choices in the presentinvention.

Furthermore, a linking group is not necessary to join the differentblocks of the present block copolymer. One can simply add successivemonomers to form successive blocks. Further, it is also possible (and insome cases advantageous) to first isolate a (co)polymer produced by thepresent ATRP process, then react the polymer with an additional monomerusing a different initiator/catalyst system (to "match" the reactivityof the growing polymer chain with the new monomer). In such a case, theproduct polymer acts as the new initiator for the further polymerizationof the additional monomer.

Thus, the present invention also encompasses end-functional homopolymershaving a formula:

    A-- (M.sup.1).sub.h !--X

and random copolymers having a formula:

    A-- (M.sup.1).sub.i (M.sup.2).sub.j !--X

    A-- (M.sup.1).sub.i (M.sup.2).sub.j (M.sup.3).sub.k !--X or

    A-- (M.sup.1).sub.i (M.sup.2).sub.j (M.sup.3).sub.k. . . (M.sup.u).sub.1 !--X

where A may be R¹¹ R¹² R¹³ C, R¹¹ R¹² R¹³ Si, (R¹¹)_(m) Si, R¹¹ R¹² N,(R¹¹)_(n) P , (R¹¹ O)_(n) P, (R¹¹) (R¹² O)P, (R¹¹)_(n) P(O), (R¹¹ O)_(n)P(O) or (R¹¹) (R ¹² O)P(O); R¹¹, R¹², R¹³ and X are as defined above;M¹, M², M³, . . . up to M^(u) are each a radically polymerizable monomer(as defined above); h, i, j, k . . . up to 1 are each average degrees ofpolymerization of at least 3; and i, j, k . . . up to 1 represent molarratios of the radically polymerizable monomers M¹, M², M³, . . . up toM^(u).

Preferably, at least one of M¹, M², M³, . . . up to M^(u) has theformula: ##STR5## wherein at least one of R¹ and R² is CN, CF₃, straightor branched alkyl of from 4 to 20 carbon atoms (preferably from 4 to 10carbon atoms, more preferably from 4 to 8 carbon atoms), C₃ -C₈cycloalkyl, aryl, heterocyclyl, C(═Y)R⁵, C(═Y)NR⁶ R⁷ and YC(═Y)R⁸, wherearyl, heterocyclyl, Y, R⁵, R⁶, R⁷ and R⁸ are as defined above; and

R³ and R⁴ are as defined above; or

R¹ and R³ are joined to form a group of the formula (CH₂)_(n') orC(═O)--Y--C(═O), where n' and Y are as defined above.

Preferably, these (co)polymers have either a weight or number averagemolecular weight of at least 250 g/mol, more preferably at least 500g/mol, even more preferably 1,000 g/mol and most preferably at least3,000 g/mol. Preferably, the (co)polymers have a polydispersity of 1.50or less, more preferably 1.35 or less, even more preferably 1.25 or lessand most preferably 1.20 or less. Although the present gels may have aweight or number average molecular weight well above 5,000,000 g/mol,from a practical perspective, the present (co)polymers and blocksthereof may have an upper weight or number average molecular weight of,e.g., 5,000,000 g/mol, preferably 1,000,000 g/mol, more preferably500,000 g/mol, and even more preferably 250,000 g/mol.

Preferred random copolymers include those prepared from any combinationof styrene, vinyl acetate, acrylonitrile, acrylamide and/or C₁ -C₈ alkyl(meth)acrylates, and particularly include those of (a) methylmethacrylate and styrene having from 10 to 75 mol % styrene, (b) methylmethacrylate and methyl acrylate having from 1 to 75 mol % methylacrylate, (c) styrene and methyl acrylate, and (d) methyl methacrylateand butyl acrylate.

The present invention also concerns block copolymers of the formula:##STR6## wherein A and X are as defined above; M¹, M², M³, . . . up toM^(u) are each a radically polymerizable monomer (as defined above)selected such that the monomers in adjacent blocks are not identical(although monomers in non-adjacent blocks may be identical) and p, q, r,. . . up to s are independently selected such that the average degree ofpolymerization and/or the weight or number average molecular weight ofeach block or of the copolymer as a whole may be as described above forthe present (co)polymers. After an appropriate end group conversionreaction (conducted in accordance with known methods), X may also be,for example, H, OH, N₃, NH₂, COOH or CONH₂.

Preferred block copolymers may have the formula ##STR7## Preferably,each block of the present block copolymers has a polydispersity of 1.50or less, more preferably 1.35 or less, even more preferably 1.25 or lessand most preferably 1.20 or less. The present block copolymer, as acomplete unit, may have a polydispersity of 3.0 or less, more preferably2.5 or less, even more preferably 2.0 or less and most preferably 1.50or less.

The present invention may be used to prepare periodic or alternatingcopolymers. The present ATRP process is particularly useful forproducing alternating copolymers where one of the monomers has one ortwo bulky substituents (e.g., where at least one of M¹, M², M³, . . . upto M^(u) are each 1,1-diarylethylene, didehydromalonate C₁ -C₂₀diesters, C₁ -C₂₀ diesters of maleic or fumaric acid, maleic anhydrideand/or maleic diimides where Y is NR⁸ as defined above!, etc.), fromwhich homopolymers may be difficult to prepare, due to stericconsiderations. Thus, some preferred monomer combinations for thepresent alternating copolymers containing "bulky" substituents includecombinations of styrene, acrylonitrile and/or C₁ -C₈ esters of(meth)acrylic acid, with maleic anhydride, C₁ -C₈ alkyl maleimidesand/or 1,1-diphenylethylene.

Copolymerization of monomers with donor and acceptor properties resultsin the formation of products with predominantly alternating monomerstructure (Cowie, "Alternating Copolymerization," Comprehensive PolymerScience, vol. 4, p. 377, Pergamon Press (1989)). These copolymers canexhibit interesting physical and mechanical properties that can beascribed to their alternating structure (Cowie, Alternating Copolymers,Plenum, New York (1985)).

So-called "alternating" copolymers can be produced using the presentmethod. "Alternating" copolymers are prepared by copolymerization of oneor more monomers having electron-donor properties (e.g., unsaturatedhydrocarbons, vinyl ethers, etc.) with one or more monomers havingelectron acceptor type properties (acrylates, methacrylates, unsaturatednitriles, unsaturated ketones, etc.). Thus, the present invention alsoconcerns an alternating copolymer of the formula: ##STR8## where A and Xare as defined above, M¹ and M² are different radically-polymerizablemonomers (as defined above), and M^(v) is one of M¹ and M² and M^(y) isthe other of M¹ and M2. However, p, q, r, . . . up to s areindependently selected such that the average degree of polymerizationand/or the weight or number average molecular weight of the copolymer asa whole or of each block may be described above for the presentend-functional or random (co)polymers. (The description "r . . . up tos" indicates that any number of blocks equivalent to those designated bythe subscripts p, q and r can exist between the blocks designated by thesubscripts r and s.)

Preferably, A is R¹¹ R¹² R¹³ C, M¹ is one or more monomers havingelectron-donor properties (e.g., C₂ -C₂₀ unsaturated hydrocarbons whichmay have one or more alkyl, alkenyl, alkynyl, alkoxy, alkylthio,dialkylamino, aryl or tri(alkyl and/or aryl)silyl substituents asdefined above e.g., isobulene or vinyl C₂ -C₁₀ ethers!, etc.) and M² isone or more monomers having electron acceptor properties(e.g.,(meth)acrylic acid or a salt thereof, C₁ -C₂₀ (meth)acrylateesters, C₃ --C₂₀ unsaturated nitriles, C₃ --C₂₀ α,β-unsaturatedaldehydes, ketones, sulfones, phosphates, sulfonates, etc., as definedabove).

Preferably, the present alternating copolymers have either a weight ornumber average molecular weight of at least 250 g/mol, more preferably500 g/mol, even more preferably 1,000 g/mol, and most preferably 3,000g/mol. Preferably, the present alternating copolymers have a maximumweight or number average molecular weight of 5,000,000 g/mol, preferably1,000,000 glmol and even more preferably 500,000 g/mol, although theupper the limit of the molecular weight of the present "living"(co)polymers is not limited. Preferably, the present alternatingcopolymers have a polydispersity of 1.50 or less, more preferably 1.35or less, even more preferably 1.25 or less and most preferably 1.20 orless.

The present random or alternating copolymer can also serve as a block inany of the present block, star, graft, comb or hyperbranched copolymers.

Where the A (or preferably R¹¹ R¹² R¹³ C) group of the initiatorcontains a second "X" group, ATRP may be used to prepare "telechelic"(co)polymers. "Telechelic" homopolymers may have the following formula:

    X--M.sub.p --(A)--M.sub.p --X

where A (preferably R¹¹ R¹² R¹³ C) and X are as defined above, M is aradically polymerizable monomer as defined above, and p is an averagedegree of polymerization of at least 3, subject to the condition that Ais a group bearing an X substituent.

Preferred telechelic homopolymers include those of styrene,acrylonitrile, C₁ -C₈ esters of (meth)acrylic acid, vinyl chloride,vinyl acetate and tetrafluoroethylene. Such telechelic homopolymerspreferably have either a weight or number average molecular weight of atleast 250 g/mol, more preferably at least 500 g/mol, even morepreferably at least 1,000 g/mol, and most preferably at least 3,000g/mol, and/or have a polydispersity of 1.50 or less, more preferably 1.3or less, even more preferably 1.2 or less and most preferably 1.15 orless. From a practical standpoint, the present alternating copolymersmay have a maximum weight or number average molecular weight of5,000,000 g/mol, preferably 1,000,000 g/mol, more preferably 500,000g/mol, and even more preferably 250,000 g/mol, although the upper limitof the molecular weight of the present "living" (co)polymers is notparticularly limited.

Block copolymers prepared by ATRP from an initiator having a second "X"group may have one of the following formulas: ##STR9## and randomcopolymers may have one of the following formulas: ##STR10## where A(preferably R¹¹ R¹² R¹³ C), X, M¹, M², M³, . . . up to M^(u), and p, q,r, . . . up to s are as defined above, subject to the condition that Ais a group bearing an X substituent.

The present invention also concerns gradient copolymers. Gradientcopolymers form an entirely new class of polymers with a controlledstructure and composition which changes gradually and in a systematicand predictable manner along the copolymer chain. Due to thiscomposition distribution and consequent unusual interchain interactions,gradient copolymers are expected to have very unique thermal properties(e.g., glass transition temperatures and/or melting points). They mayalso exhibit unprecedented phase separation and uncommon mechanicalbehavior, and may provide unique abilities as surfactants or asmodifiers for blending incompatible materials.

Gradient copolymers can be obtained in a system without a significantchain-breaking reaction, such as ATRP. To control the copolymercomposition, it is beneficial to maintain continuous growth of thepolymer chain and regulate the comonomers' feed composition during thecourse of the reaction. Otherwise, the distribution of the monomer unitsalong the polymer chain may be random or block-like.

To date, there are no publications on the subject of gradientcopolymers. The closest examples described so far are tapered copolymersprepared through living anionic polymerization (Sardelis et al, Polymer,25, 1011 (1984) and Polymer, 28, 244 (1987); Tsukuhara et al, Polym. J.,12, 455 (1980)). Tapered copolymers differ from gradient copolymerssince they retain block-like character despite the composition gradientin the middle block. Additionally, the compositional gradient of taperedpolymers is inherent and cannot be changed or controlled.

Gradient copolymers may be prepared via ATRP copolymerization of two ormore monomers with different homopolymerization reactivity ratios (e.g.,r¹ >>r₂, where r¹ may be greater than 1 and r₂ may be less than 1). Suchcomonomers usually do not copolymerize randomly (Odian, Principles ofPolymerization, 3rd ed., John Wiley & Sons, New York, p. 463 (1991)).For example, in conventional radical polymerization, a mixture ofhomopolymers is obtained.

In the present controlled system, where the polymer chain is notterminated at any stage of the reaction, initially only the more (ormost) reactive monomer reacts until its concentration decreases to sucha level that the less (or second most) reactive monomer begins toincorporate into the growing polymer chains. The less reactive monomeris gradually incorporated into the polymer chain to a greater extent,and its content in the chain increases, as the more reactive monomer isfurther consumed. Finally, only the least reactive monomer is present inthe system and as it reacts, it forms a block of the least reactivemonomer at the end of the chain. The gradient of composition in such acopolymer is controlled by the difference in the reactivity ratios andthe rate with which each of the monomers reacts. It might also beconsidered an inherent control over the copolymer's composition, whichcan be altered by intentionally changing the concentration of one ormore of the monomers.

Thus, in an example of the gradient copolymerization including twodistinct monomers, the polymerizing step of the present method ofcontrolled atom or group transfer polymerization may comprisepolymerizing first and second radically polymerizable monomers presentin amounts providing a molar ratio of the first monomer to the secondmonomer of from a:b to b:a, where a and b are each from 0 to 100 and(a+b)=100, then adding an additional amount of the first and/or secondmonomer providing a molar ratio of the first monomer to the secondmonomer of from c:d to d:c, where c differs from a, d differs from b and(c+d)=100, and if desired, repeating as often as desired the adding stepsuch that if c>a, the molar proportion (or percentage) of the firstmonomer increases, but if d>b, the molar proportion (or percentage) ofthe second monomer increases. The adding step(s) may be continuous, inintermittent portions or all at once.

Thus, the present invention also encompasses a gradient copolymer of theformula:

    A--M.sup.1.sub.n --(M.sup.1.sub.a M.sup.2.sub.b).sub.x --. . . --(M.sup.1.sub.c M.sup.2.sub.d).sub.y --M.sup.2.sub.m --X

where A and X are as defined above, M¹ and M² areradically-polymerizable monomers (as defined above) having differentreactivities (preferably in which the ratio of homopolymerization and/orcopolymerization reactivity rates are at least 1.5, more preferably atleast 2 and most preferably at least 3), a, b, c and d are non-negativenumbers independently selected such that a+b=c+d=100, wherein the a:bratio is from 99:1 to 50:50, the c:d ratio is from 50:50 to 99:1, andthe molar proportion of M¹ to M² gradually decreases along the length ofthe polymer chain from a:b to c:d, and n, m, x and y are independentlyan integer of at least 2, preferably at least 3, more preferably atleast 5 and most preferably at least 10. The weight or number averagemolecular weight of each block or of the copolymer as a whole may be asdescribed above for the present (co)polymers. Preferably, A is R¹¹ R¹²R¹³ C, and X is a halogen.

To determine the gradient, the copolymerization can be intermittentlysampled, and the molar proportion of units of the copolymercorresponding to each monomer determined in accordance with knownmethods. As long as the proportion of one monomer increases as theother(s) decrease(s) during the course of the copolymerization, themolar proportion of the one monomer increases along the length of thepolymer chain as the other(s) decrease(s).

Alternatively, the decrease of the monomer ratio along the length of thepolymer chain a:b to c:d can be determined in accordance with thenumbers of monomer units along the polymer chain. The number ofsubblocks must be smaller than the number of monomeric units in eachsubblock, but the subblocks may overlap by a number of monomer unitssmaller than the size of the subblock. For example, where the centralblock of the polymer contains 6 monomeric units, the ratios may bedetermined for two 3-unit subblocks (e.g., (3-mer)-(3-mer)). Where thecentral block of the polymer contains, for example 9 monomeric units,the ratios may be determined for three 4-unit subblocks where thecentral subblock overlaps each terminal subblock by one monomer unit(e.g., (4-mer)-(overlapping 4-mer)-(4-mer). Where the central block ofthe polymer contains, for example, from 10 to 50 monomeric units, theratios may be determined for 5- to 10-unit subblocks (e.g.,(5-mer)-(5-mer), (6-mer)-(8-mer)-(6-mer), (10-mer)-(10-mer),(5-mer)-(5-mer)-(5-mer)-(5-mer), etc.). Where the central block of thepolymer contains, for example, from 51 to 380 monomeric units, theratios may be determined for 10- to 20-unit subblocks; etc. Suchcopolymers can be prepared by carefully controlling the molar ratios ofmonomers to each other and to initiator or dormant polymer chains.

In a further embodiment, the relative proportions of first monomer tosecond monomer are controlled in a continuous manner, using for exampleby adding the second monomer via a programmable syringe or feedstocksupply pump.

When either the initiator or monomer contains a substituent bearing aremote (i.e., unconjugated) ethylene or acetylene moiety, ATRP can beused to prepare cross-linked polymers and copolymers.

The present invention is also useful for forming so-called "star"polymers and copolymers. Thus, where the initiator has three or more "X"groups, each of the "X" groups can serve as a polymerization initiationsite. Thus, the present invention also encompasses star (co)polymers ofthe formula: ##STR11## where A' is the same as A with the proviso thatR¹¹, R¹² and R¹³ combined contain from 2 to 5 X groups, where X is asdefined above; M¹, M², M³, . . . M^(u) are as defined above for thepresent block copolymers; and z is from 3 to 6. Preferably, A' is R¹¹R¹² R¹³ C, and X is halogen (preferably chlorine or bromine).

Initiators suitable for use in preparing the present star (co)polymersare those in which the A (or preferably R¹¹ R¹² R¹³ C) group possessesat least three substituents which can be "X" (as defined above).Preferably, these substituents are identical to "X". Examples of suchinitiators include compounds of the formula C₆ H_(x) (CH₂ X)_(y) orCH_(x') (CH₂ X)_(y'), where X is a halogen, x+y=6, x'+y'=4 and y and y'are each ≧3. Preferred initiators of this type include2,2-bis(chloromethyl)-1,3-dichloropropane,2,2-bis(bromomethyl)-1,3-dibromopropane), α,α',α"-trichloro- and α,α',α"-tribromocumene, and tetrakis- and hexakis(α-chloro- andα-bromomethyl)benzene), the most preferred beinghexakis(α-bromomethyl)benzene.

Branched and hyperbranched polymers may also be prepared in accordancewith the present invention. The synthesis of hyperbranched polymers hasbeen explored to develop dendritic molecules in a single, one-potreaction.

Conventional hyperbranched polymers are obtained by the reaction of AB₂monomers in which A and B are moieties containing functional groupscapable of reacting with each other to form stable bonds. Because of theAB₂ structure of the monomers, reaction of two monomers results in theformation of a dimer with one A group and three B groups. This processrepeats itself by reaction with either monomer, dimer, trimer, etc., ina similar fashion to provide step-wise growth of polymers.

The resulting polymer chains have only one A group and (n+1) B groups,where n is the number of repeat units. Polymers resulting from thesereactions are sometimes highly functionalized. These polymers, however,do not have perfectly symmetrical architectures, but rather, are ofirregular shapes. This may be due to uneven growth of the macromoleculein various directions.

The present hyperbranched polymers have some of the qualities ofdendrimers, but may lack some properties of perfect dendrimers. Thecationic process described by Frechet et al. (Science 269, 1080 (1995))differs from the present synthesis of hyperbranched polymers not only inthe mechanism of polymerization, but also by extending the reaction toprimary benzyl halides.

The present invention also concerns a process for preparinghyperbranched polymers (e.g., hyperbranched polystyrene) by atom orgroup transfer radical polymerization (ATRP), preferably in "one-pot"(e.g., in a single reaction sequence without substantial purificationsteps, and more specifically, in a single reaction vessel without anyintermediate purification steps), using the present process and at leastone radically polymerizable monomer in which at least one of R¹, R², R³and R⁴ also contains a radically transferable X group, optionally in theabsence of an initiator (or if an initiator is used, the X group of themonomer may be the same or different from the X group of the initiator).

For example, commercially available p-chloromethylstyrene (p-CMS) may bepolymerized in the presence of a transition metal compound (e.g., Cu(I))and ligand (e.g., 2,2'-bipyridyl, or "bipy"). A demonstrative example ofthe copolymerization of styrene and p-CMS, and its comparison with alinear standard, is presented in the Examples below.

In fact, the monomer may also act as initiator (e.g., thehomopolymerization of p-CMS in the presence of Cu(I) and bipy). It ispossible to remove the chlorine atom at the benzylic positionhomolytically, thus forming Cu(II)Cl₂ and a benzyl radical capable ofinitiating the polymerization of monomer through the double bonds (seeScheme 3). This results in the formation of a polymer chain with pendantgroups consisting of p-benzyl chloride. Also, the polymer has a doublebond at the chain end which can be incorporated into a growing polymerchain.

Thus, the present invention also concerns a hyperbranched (co)polymer ofthe formula: ##STR12## where M¹ is a radically polymerizable monomerhaving both a carbon-carbon multiple bond and at least one X group (asdefined above); M², M³. . . up to M^(u) are radically polymerizablemonomers (as defined above); a, b, c . . . up to d are numbers of atleast zero such that the sum of a, b, c . . . up to d is at least 2,preferably at least 3, more preferably at least 4 and most preferably atleast 5; e is the sum of the products of (i) a and the number of Xgroups on M¹, (ii) b and the number of X groups on M², (iii) c and thenumber of X groups on M³. . . up to (iv) d and the number of X groups onM^(u) ; f≦e and (g+h+i+j+k)=e.

The formula "M¹ --(M¹ _(a) M² _(b) M³ _(c). . . M^(u) _(d))--X_(e) "represents a "perfect" hyperbranched polymer, in which each "X" group isat the end of a chain or branch of monomeric units. (In the presenthyperbranched (co)polymer, a "chain" may be defined as the longestcontinuous series of monomeric units of a polymer. A "branch" may bedefined as any covalently-bound series of monomer units in the polymercontaining a number of monomeric units smaller than the "chain".) Theformula: ##STR13## represents those (co)polymers in which one or more"X" groups are bound to non-terminal monomer units (i.e., monomer unitsnot at the end of a branch or chain).

In fact, the present invention also encompasses those (co)polymers inwhich the "X" substituent is located at either or both ends of the(co)polymer chain, on an internal monomeric unit, or any combinationthereof. "Internal" X groups can be put into place by incorporating intothe polymer chain a monomer having a substituent encompassed by thedefinition of "X" above.

In the present hyperbranched (co)polymer, the number of branches will beat most 2.sup.(a-1) -1, assuming all "x" groups are active in subsequentATRP steps. Where, for example, a number "h" of "X" groups fail to reactin subsequent ATRP steps (e.g., where one of the 1° or 2° Cl groups on abranch in the octamer shown in Scheme 3 below does not react insubsequent ATRP steps, but the other does), a product of the formula:##STR14## is formed. The subsequent number of branches is reduced by2^(h).

The present invention also concerns cross-linked polymers and gels, andprocesses for producing the same. By conducting the polymerizing stepwhich produces the present branched and/or hyperbranched (co)polymersfor a longer period of time, gelled polymers may be formed. For example,by increasing the amount or proportion of p-chloromethyl styrene in thereaction mixture (e.g., relative to solvent or other monomer(s)), thecross-link density may be increased and the reaction time may belowered. ##STR15##

(Typically, a polymerizing step in any aspect of the present inventionmay be conducted for a length of time sufficient to consume at least25%, preferably at least 50%, more preferably at least 75%, even morepreferably at least 80% and most preferably at least 90% of monomer.Alternatively, the present polymerizing step may be conducted for alength of time sufficient to render the reaction mixture too viscous tostir, mix or pump with the stirring, mixing or pumping means being used.However, the polymerizing step may generally be conducted for anydesired length of time.)

The present invention also encompasses graft or "comb" copolymers,prepared by sequential polymerizations. For example, a first (co)polymermay be prepared by conventional radical polymerization, then a second(or one or more further) (co)polymer chains or blocks may be graftedonto the first (co)polymer by ATRP; a first (co)polymer may be preparedby ATRP, then one or more further (co)polymer chains or blocks may begrafted onto the first (co)polymer by conventional radicalpolymerization; or the first (co)polymer may be prepared and the further(co)polymer chains or blocks may be grafted thereonto by sequentialATRP's.

A combination of ATRP and one or more other polymerization methods canalso be used to prepare different blocks of a linear or star blockcopolymer (i.e., when extending one or several chains from a base(co)polymer). Alternatively, a combination of ATRP and one or more otherpolymerization methods can be used to prepare a "block homopolymer", inwhich distinct blocks of a homopolymer having one or more differentproperties (e.g., tacticity) are prepared by different polymerizationprocesses. Such "block homopolymers" may exhibit microphase separation.

Thus, the present invention further concerns a method of preparing agraft or "comb" (co)polymer which includes the present ATRP process,which may comprise reacting a first (co)polymer having either aradically transferable X substituent (as defined above) or a group thatis readily converted (by known chemical methods) into a radicallytransferable substituent with a mixture of (i) transition metal compoundcapable of participating in a reversible redox cycle with the first(co)polymer, (ii) a ligand (as defined above) and (iii) one or moreradically polymerizable monomers (as defined above) to form a reactionmixture containing the graft or "comb" (co)polymer, then isolating theformed graft or "comb" (co)polymer from the reaction mixture. The methodmay further comprise the step of preparing the first (co)polymer byconventional radical, anionic, cationic or metathesis polymerization orby a first ATRP, in which at least one of the monomers has a R¹ --R⁴substituent which is encompassed by the description of the "X" groupabove. Where the catalyst and/or initiator used to prepare the first(co)polymer (e.g., a Lewis acid used in conventional cationicpolymerization, a conventional metathesis catalyst having a metal-carbonmultiple bond, a conventional organolithium reagent) may be incompatiblewith the chosen ATRP initiation/catalyst system, or may produce anincompatible intermediate, the process may further comprise the step ofdeactivating or removing the catalyst and/or initiator used to preparethe first (co)polymer prior to the grafting step (i.e., reacting thefirst (co)polymer with subsequent monomer(s) by ATRP).

Alternatively, the method of preparing a graft or "comb" (co)polymer maycomprise preparing a first (co)polymer by the present ATRP process, thengrafting a number of (co)polymer chains or blocks onto the first(co)polymer by forming the same number of covalent bonds between thefirst (co)polymer and one or more polymerizable monomers (e.g., byconventional radical polymerization, conventional anionicpolymerization, conventional cationic polymerization, conventionalmetathesis polymerization, or the present ATRP process) polymerizing thepolymerizable monomer(s) in accordance with the conventional or ATRPprocesses mentioned to form a reaction mixture containing the graft or"comb" (co)polymer, then isolating the formed graft or "comb"(co)polymer from the reaction mixture.

Preferably the X substituent on the first (co)polymer is Cl or Br.Examples of preferred monomers for the first (co)polymer thus includeallyl bromide, allyl chloride, vinyl chloride, 1- or 2-chloropropene,vinyl bromide, 1,1- or 1,2-dichloro- or dibromoethene, trichloro- ortribromoethylene, tetrachloro- or tetrabromoethylene, chloroprene,1-chlorobutadiene, 1- or 2-bromobutadiene, vinyl chloroacetate, vinyldichloroacetate, vinyl trichloroacetate, etc. More preferred monomersinclude vinyl chloride, vinyl bromide, vinyl chloroacetate andchloroprene. It may be necessary or desirable to hydrogenate (by knownmethods) the first (co)polymer (e.g., containing chloroprene units)prior to grafting by ATRP.

Thus, the present invention also encompasses graft or "comb"(co)polymers having a formula: ##STR16## where R" is a first (co)polymerremainder from a first copolymer having a formula RX_(f), f≧e; e is anumber having an average of at least 2.5, preferably at least 3.0, morepreferably at least 5.0, and most preferably at least 8.0; X is asdefined above (and is preferably a halogen); M¹, M², M³, . . . up toM^(u) are each a radically polymerizable monomer (as defined above); p,q, r and s are selected to provide weight or number average molecularweights for the corresponding block is at least 100 g/mol, preferably atleast 250 g/mol, more preferably at least 500 g/mol and even morepreferably at least 1,000 g/mol; and i, j, k . . . up to 1 representmolar ratios of the radically polymerizable monomers M¹, M², M³, . . .up to M^(u). The polydispersity, average degree of polymerization and/orthe maximum weight or number average molecular weight of the (co)polymeror component thereof (e.g., base polymer or graft side-chain) may be asdescribed above.

Preferred graft copolymers include those in which the first (co)polymerincludes at least three units of vinyl chloride, vinyl bromide, or a c₂--c₃ -alkenyl halo-c₁ --c₂₀ -alkanoate ester (e.g., vinylchloroacetate). More preferred graft copolymers include those in whichthe first (co)polymer is an N-vinylpyrrolidone/vinyl chloroacetatecopolymer containing on average at least three units of vinylchloroacetate per chain, in which polystyrene chains are graftedthereonto by ATRP using the chloroacetate moiety as initiator. Suchgraft copolymers are expected to be useful to make, e.g., disposablecontact lenses.

In the present copolymers, each of the blocks may have a number averagemolecular weight in accordance with the homopolymers described above.Thus, the present copolymers may have a molecular weight whichcorresponds to the number of blocks (or in the case of star polymers,the number of branches times the number of blocks) times the numberaverage molecular weight range for each block.

Polymers and copolymers produced by the present process havesurprisingly low polydispersities for (co)polymers produced by radicalpolymerization. Typically, the ratio of the weight average molecularweight to number average molecular weight ("M^(w) /M_(n) ") is ≦1.5,preferably ≦1.4, and can be as low as 1.10 or less.

Because the "living" (co)polymer chains retain an initiator fragment inaddition to an X or X' as an end group or as a substituent in thepolymer chain, they may be considered end-functional or in-chain(multi)functional (co)polymers. Such (co)polymers may be used directlyor be converted to other functional groups for further reactions,including crosslinking, chain extension, reactive injection molding(RIM), and preparation of other types of polymers (such aspolyurethanes, polyimides, etc.).

The present invention provides the following advantages:

A larger number and wider variety of monomers can be polymerized byradical polymerization, relative to ionic and other chainpolymerizations;

Polymers and copolymers produced by the present process exhibit a lowpolydispersity (e.g., M_(w) /M_(n) ≦1.5, preferably ≦1.4, morepreferably ≦1.25, and most preferably, ≦1.10), thus ensuring a greaterdegree of uniformity, control and predictability in the (co)polymerproperties;

One can select an initiator which provides an end group having the samestructure as the repeating polymer units (1-phenylethyl chloride asinitiator and styrene as monomer);

The present process provides high conversion of monomer and highinitiator efficiency;

The present process exhibits excellent "living" character, thusfacilitating the preparation of block copolymers which cannot be formedby ionic processes;

Polymers produced by the present process are well-defined and highlyuniform, comparable to polymers produced by living ionic polymerization;

End-functional initiators (e.g., containing COOH, OH, NO₂, N₃, SCN,etc., groups) can be used to provide an end-functional polymer in onepot, and/or polymer products with different functionalities at each end(e.g., in addition to one of the above groups at one end, acarbon-carbon double bond, epoxy, imino, amide, etc., group at anotherend);

The end functionality of the (copolymers produced by the present process(e.g., Cl, Br, I, CN, CO₂ R) can be easily converted to other functionalgroups (e.g., Cl, Br and I can be converted to OH or NH₂ by knownprocesses, CN or CO₂ R can be hydrolyzed to form a carboxylic acid byknown processes, and a carboxylic acid may be converted by knownprocesses to a carboxylic acid halide), thus facilitating their use inchain extension processes (e.g., to form long-chain polyamides,polyurethanes and/or polyesters);

In some cases (e.g., where "X" is Cl, Br and I), the end functionalityof the polymers produced by the present process can be reduced by knownmethods to provide end groups having the same structure as the repeatingpolymer units.

Even greater improvements can be realized by using (a) an amount of thecorresponding reduced or oxidized transition metal compound whichdeactivates at least part of the free radicals which may adverselyaffect polydispersity and molecular weight control/predictability and/or(b) polymerizing in a homogeneous system or in the presence of asolubilized initiating/catalytic system;

A wide variety of (co)polymers having various structures and topologies(e.g., block, random, graft, alternating, tapered (or "gradient"), star,"hyperbranched", cross-linked and water-soluble copolymers andhydrogels) which may have certain desired properties or a certaindesired structure may be easily synthesized; and

Certain such (co)polymers may be prepared using water as a medium.

Other features of the present invention will become apparent in thecourse of the following descriptions of exemplary embodiments which aregiven for illustration of the invention, and are not intended to belimiting thereof.

EXAMPLES Example 1:

The effect of air exposure upon heterogeneous ATRP of styrene. Thefollowing amounts of reagents were weighed into each of three glasstubes under an inert atmosphere in a nitrogen-filled dry box: 11.0 mg(4.31×10⁻² mol) of (bipy)CuCl!₂ (Kitagawa, S.; Munakata, M. Inorg. Chem.1981, 20, 2261), 1.00 mL (0.909 g, 8.73 mmol) of dry, deinhibitedstyrene, and 6.0 μL (6.36 mg, 4.52×10⁻² mmol) of dry1-phenylethylchloride 1-PECl!.

The first tube was sealed under vacuum without exposure to air.

The second tube was uncapped outside of the dry box and shaken whileexposed to ambient atmosphere for two minutes. The tube was thenattached to a vacuum line, the contents were frozen using liquidnitrogen, the tube was placed under vacuum for five minutes, thecontents were thawed, and then argon was let into the tube. This"freeze-pump-thaw" procedure was repeated before the tube was sealedunder vacuum, and insured that dioxygen was removed from thepolymerization solution.

The third tube was exposed to ambient atmosphere for 10 minutes andsubsequently sealed using the same procedure.

The three tubes were heated at 130° C. for 12 h using a thermostattedoil bath. Afterwards, the individual tubes were broken, and the contentswere dissolved in tetrahydrofuran THF! and precipitated into CH₃ OH.Volatile materials were removed from the polymer samples under vacuum.Molecular weights and polydispersities were measured using gelpermeation chromatography GPC! relative to polystyrene standards.Results are shown in Table 1 below.

                  TABLE 1                                                         ______________________________________                                        Results of the air exposure experiments                                       Time of Air                                                                   Exposure   Yield        M.sub.n PDI                                           ______________________________________                                        None       100          18,200  1.61                                           2 min      70          13,200  1.59                                          10 min      61          11,900  1.39                                          ______________________________________                                    

Example 2:

General procedure for the homogeneous ATRP of styrene. The followingamounts of reagents were weighed into glass tubes under ambientatmosphere: 12.0 mg (8.37×10⁻² mmol) of CuBr, 1.00 mL (0.909 g, 8.73mmol) of deinhibited styrene, and 12.0 μL (16.3 mg, 8.8×10⁻² mmol) of1-phenylethylbromide 1-PEBr!. For polymerizations using dNbipy, 72.0 mg(0.175 mmol) of the ligand was added, for dTbipy, 47.0 mg (0.175 mmol)was added, and for dHbipy, 62.0 mg (0.175 mmol) was added. Two"freeze-pump-thaw" cycles (described above) were performed on thecontents of each tube in order to insure that dioxygen was removed fromthe polymerization solution. Each tube was sealed under vacuum.

The tubes were placed in an oil bath thermostatted at 100° C. At timedintervals, the tubes were removed from the oil bath and cooled to 0° C.using an ice bath in order to quench the polymerization. Afterwards, theindividual tubes were broken, and the contents were dissolved in 10.0 mlof THF. Catalyst could be removed by passing the polymer solutionthrough an activated alumina column. Percent conversion of each samplewas measured using gas chromatography, and molecular weights andpolydispersities were measured using GPC relative to polystyrenestandards. Results are shown in Tables 2 and 3 below.

                  TABLE 2                                                         ______________________________________                                        Molecular weight data for the homogeneous ATRP of                             styrene using dTbipy as the ligand.                                                     (%)                                                                 Time (min)                                                                              Conversion   M.sub.4  (GPC)                                                                         PDI (GPC)                                     ______________________________________                                         60         14.5       1250     1.08                                          120       20           1610     1.09                                          181       28           2650     1.09                                          270       43           3880     1.08                                          303       49           4670     1.10                                          438       59           5700     1.08                                          ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Molecular weight data for the homogeneous ATRP of                             styrene using dHbipy as the ligand.                                                     %                                                                   Time (min)                                                                              Conversion   M.sub.n  (GPC)                                                                         PDI (GPC)                                     ______________________________________                                         60       31           2860     1.05                                          124       45           3710     1.04                                          180       58           6390     1.04                                          240       78           8780     1.05                                          390       90           9230     1.06                                          ______________________________________                                    

Example 3:

General procedures for the determination of the effect of addedcopper(II) on homogeneous ATRP of styrene. dhbipy was prepared accordingto the procedure of Kramer et al (Angew. Chem., Intl. Ed. Engl. 1993,32, 703). dTbipy was prepared according to the procedure of Hadda andBozec (Polyhedron 1988, 7, 575). CuCl was purified according to theprocedure of Keller and Wycoff (Inorg. Synth. 1946, 2, 1).

Method 1: Weighed addition of the transition metal reagents

In a dry box, appropriate amounts of pure CuCl, pure CuCl₂, bipyridylligand, dry 1-PEC1 and 1,4-dimethoxybenzene added to a 100 mL Schlenkflask equipped with a magnetic stir bar. The flask was fitted with arubber septum, removed from the dry box, and attached to a Schlenk line.The appropriate amounts of dry, deinhibited styrene and high boilingsolvent were added to the flask, and the septum was fixed in place usingcopper wire. The flask, with the polymerization solution always under anargon atmosphere, was heated at 130° C. using a thermostatted oil bath,and upon heating a homogeneous red-brown solution formed. Aliquots ofthe polymerization solution (2.00 mL) were removed at timed intervalsusing a purged syringe and dissolved in 10.0 ml of THF. Percentconversion of each sample was measured using gas chromatography, andmolecular weights and polydispersities were measured using GPC relativeto polystyrene standards.

Polymerization #1 (no CuCl₂):

8.5 mg (0.86 mmol) of CuCl

0.120 mL (0.91 mmol) of 1-PECl

46.6 mg (1.74 mmol) of dTbipy

20.0 mL (0.175 mol) of styrene

20.0 g of p-dimethoxybenzene

                  TABLE 4                                                         ______________________________________                                        Results of polymerization #1                                                            %                                                                   Time (min)                                                                              Conversion   M.sub.n  (GPC)                                                                         PDI (GPC)                                     ______________________________________                                        38        12            2,910   1.60                                          82        19            3,700   1.60                                          120       23            5,370   1.57                                          177       46            8,480   1.46                                          242       58           11,500   1.37                                          306       66           13,300   1.33                                          373       69           14,400   1.29                                          1318      93           19,000   1.22                                          ______________________________________                                    

Polymerization #2 (3 mol % CUCl₂):

8.9 mg (0.90 mmol) of CuCl

0.4 mg (0.03 mmol) of CuCl₂

0.120 mL (0.91 mmol) of 1-PECl

47.1 mg (1.75 mmol) of dTbipy

20.0 mL (0.175 mol) of styrene

20.0 g of p-dimethoxybenzene

                  TABLE 5                                                         ______________________________________                                        Results of polymerization #2                                                            %                                                                   Time (min)                                                                              Conversion   M.sub.n  (GPC)                                                                         PDI (GPC)                                     ______________________________________                                        37        0            0        --                                            85        8            1,870    1.44                                          123       22.5         3,280    1.41                                          194       30.5         4,470    1.40                                          256       39           6,920    1.31                                          312       43           9,340    1.27                                          381       48           10,000   1.25                                          1321      79           15,490   1.21                                          1762      83           15,300   1.21                                          ______________________________________                                    

Method 2: Addition of stock solutions of the copper reagents

The polymerizations were conducted as in the general procedure for thehomogeneous ATRP of styrene, except that stock solutions of thedipyridyl ligand with CuBr, and separately, CuBr₂ in styrene wereprepared and added to 1-PEBr in the glass tube before removal from thedry box and sealing.

Polymerization #1 (no CuBr₂):

4.5×10⁻² mmol of CuBr

6.2 μL (4.5×10⁻² MMol) of 1-PEBr

32.0 mg (9.0×10⁻² mmol) of dHbipy

0.5 mL (4.36 mol) of styrene

                  TABLE 6                                                         ______________________________________                                        Results of polymerization #1                                                            %                                                                   Time (min)                                                                              Conversion   M.sub.n  (GPC)                                                                         PDI (GPC)                                     ______________________________________                                         70       38           4,510    1.08                                          120       64           6,460    1.09                                          160       68           6,710    1.10                                          200       72           8,290    1.11                                          240       82           9,480    1.14                                          300       86           10,180   1.13                                          ______________________________________                                    

Polymerization #2 (1.0 Mol % of CuBr₂):

4.5×10⁻² mmol of CuBr

4.5×10⁻⁴ mmol of CuBr₂

6.2 μL (4.5×10⁻² MMol) of 1-PEBr

9.0×10⁻² mmol of dHbipy

0.5 mL (4.36 mol) of styrene

                  TABLE 7                                                         ______________________________________                                        Results of polymerization #2                                                            %                                                                   Time (min)                                                                              Conversion   M.sub.n  (GPC)                                                                         PDI (GPC)                                     ______________________________________                                         50        5           1210     1.07                                          105       18           2870     1.05                                          165       39           4950     1.06                                          174       40           4990     1.06                                          300       68           6470     1.07                                          ______________________________________                                    

Example 4:

ATRP of water-soluble monomers

General procedure for the polymerization of water soluble monomers.Under ambient conditions, a glass tube was charged with the appropriateamounts of copper(I) halide (unpurified), bipy, initiator, and monomer.Water, if used, was then added. Two "freeze-pump-thaw" cycles (describedabove) were performed on the contents of each tube in order to insurethat dioxygen was removed from the polymerization solution. Each tubewas sealed under vacuum, and then placed in a thermostatted oil bath at80° C. or 100° C. for 12 h. Afterwards, the individual tubes werebroken.

(a) P(NVP). For N-vinyl pyrrolidone, the contents were dissolved in 10.0ml of THF. Percent conversion of each sample was measured using gaschromatography.

Bulk conditions:

12.1 mg (8.4×10⁻² mmol) of CuBr

28.1 mg (0.18 mmol) of bipy

4.0 μl (6.2 mg, 4.1×10⁻² mmol) of bromomethyl acetate

1.00 mL (0.980 g, 8.82 mmol) of N-vinyl pyrrolidone

Heated at 100° C. for 12 h

% Conversion=100

Aqueous conditions:

13.7 mg (9.6×10⁻² mmol) of CuBr

30.1 mg (0.19 mmol) of bipy

4.0 μl (6.2 mg, 4.1×10⁻² mmol) of bromomethyl acetate

1.00 mL (0.980 g, 8.82 mmol) of N-vinyl pyrrolidone

1.00 mL of water

Heated at 100° C. for 12 h

% Conversion=80

(b) P(acrylamide). For acrylamide, the contents were dissolved in 50 mLof water and precipitated into 200 mL of CH₃ OH. The polymer wasisolated by filtration, and volatile materials were removed undervacuum.

Conditions:

10.7 mg (7.5×10⁻² mmol) of CuBr

39.3 mg (0.25 mmol) of bipy

8.0 μl (12.0 mg, 7.2×10⁻² mmol) of methyl-2-bromopropionate

1.018 g (14.3 mmol) of acrylamide

1.00 mL of water

Heated at 100° C. for 12 h.

Yield: 0.325 (32%) of a white solid

(c) P(HEMA). For 2-hydroxyethyl methacrylate, the contents weredissolved in 50 mL of dimethyl formamide DMF! and precipitated into 200mL of diethyl ether. The solvent was decanted from the oily solid, andthe residue was dissolved in 25 mL of DMF. To this solution, 25 mL ofacetyl chloride was added and the solution was heated at reflux for 4 h.Then, 50 mL of THF was added and the solution was poured into 250 mL ofCH₃ OH. The resulting suspension was isolated by centrifugation, and thematerial was repreciptated from 50 mL of THF using 250 mL of CH₃ OH. Themolecular weight and polydispersity of the sample was measured using GPCrelative to polystyrene standards.

Conditions:

11.1 mg (2.1×10⁻² mol) of Cu(bipy)₂ ⁺ (PF₆)⁻

6.0 μl (8.0 mg, 4.1×10⁻² mmol) of ethyl-2-bromoisobutyrate

1.00 mL (1.07 g, 5.5 mmol) of 2-hydroxyethyl methacrylate

1.00 mL of water

Heated at 80° C. for 12 h.

Mn=17,400; PDI=1.60

Examples 5-8:

Random copolymers

ATRP allows preparation of random copolymers of a variety of monomersproviding a broad range of compositions, well controlled molecularweights and narrow molecular weight distributions.

Example 5:

Preparation of random copolymers of methyl methacrylate and styrene

(a) Copolymers containing 20% styrene

0.007 g of CuBr, 0.0089 g of 2,2'-bipyridyl and 0.067 ml ofethyl-2-bromoisobutyrate was added to a degassed mixture of styrene(0.25 ml) and methyl methacrylate (0.75 ml) and the reaction mixture washeated to 100° C. After 2.5 hrs. the polymerization was interrupted, andthe resulting polymer was precipitated on methanol and purified byreprecipitation from THF/methanol. The yield of the copolymer was 35%.

The composition of the copolymer was determined by NMR to be 20 mol. %styrene. Molecular weight, M_(n), of the copolymer was 11,000 andpolydispersity (Mw/Mn)=1.25, as obtained from GPC relative topolystyrene standards.

(b) Copolymers containing 50% styrene

0.007 g of CuBr, 0.0089 g of 2,2'-bipyridyl and 0.067 ml ofethyl-2-bromoisobutyrate was added to a degassed mixture of styrene (0.5ml) and methyl methacrylate (0.5 ml). The reaction mixture was heated to100° C. After 3.5 hrs., the polymerization was interrupted, and theresulting polymer was precipitated in methanol and purified byreprecipitation from THF/methanol. The yield of the copolymer was 18%.

The composition of the copolymer was determined by NMR to be 50% (bymoles) of styrene. Molecular weight, M_(n), of the copolymer was 9,000and polydispersity Mw/Mn=1.27, as obtained from GPC relative topolystyrene standards.

(c) Copolymers containing 65% styrene

0.007 g of CuBr, 0.0089 g of 2,2'-bipyridyl and 0.067 ml ofethyl-2-bromoisobutyrate was added to a degassed mixture of styrene(0.75 ml) and methyl methacrylate (0.25 ml). The reaction mixture washeated to 100° C. After 2.0 hrs., the polymerization was interrupted,and the resulting polymer was precipitated in methanol and purified byreprecipitation from THF/methanol. The yield of the copolymer was 16%.

The composition of the copolymer was determined by NMR to be 65% (bymoles) of styrene. Molecular weight, M_(n), of the copolymer was 6,000and polydispersity Mw/Mn=1.25, as obtained from GPC relative topolystyrene standards.

Example 6:

Random Copolymerization Between Styrene (70 mol %) and Acrylonitrile (30mol %)

2,2'-Bipyridyl (0.1781 g), dimethoxybenzene (20 g), and Cu(I) Cl (0.0376g) were added to a 100 ml flask, which was sealed with a rubber septumand copper wire. The flask was placed under vacuum and then back-filledwith argon. This was repeated two more times. Styrene (17.2 ml) andacrylonitrile (4.2 ml) were then added via syringe. The monomers hadbeen previously deinhibited by passing through a column of alumina anddegassed by bubbling argon through the monomer for fifteen minutes.1-Phenylethyl chloride (0.0534 g) was then added to the reaction mixtureby syringe, and the reaction was heated to 130° C. Samples were taken(0.5 ml each). Conversion was determined by ¹ H NMR, and the Mn andpolydispersity (PD) determined by GPC. The samples were then purified bydissolution in THF and precipitation into methanol three times. Thepurified polymer was then evaluated for acrylonitrile content by ¹ HNMR. The differences in monomer reactivities (reactivity ratio) mayprovide a compositional gradient. Table 8 lists the results.

                  TABLE 8                                                         ______________________________________                                        Time (h)                                                                              Conversion (%)                                                                            M.sub.n  PD    % Acrylonitrile                            ______________________________________                                        2.0     27.0         8160    1.65  54.2                                       5.25    29.6         9797    1.51  35.6                                       8.0     39.4        11131    1.44  40.8                                       21.0    53.6        16248    1.31  34.1                                       ______________________________________                                    

Example 7:

Preparation of random copolymer of styrene and methyl acrylate

0.010 g of CuBr, 0.0322 g of 2,2'-bipyridyl and 0.010 ml ofethyl-2-bromoisobutyrate was added to a degassed mixture of methylacrylate (0.42 ml) and styrene (1.00 ml) and the reaction mixture washeated to 90° C. After 14 hrs., the polymerization was interrupted andthe resulting polymer was precipitated on methanol and purified byreprecipitation from THF/methanol. The yield of the copolymer was 87%.

The composition of the copolymer was determined by NMR to be 40% (bymoles) of styrene. Molecular weight, M_(n), of the copolymer was 22,000and polydispersity Mw/Mn=1.18, as obtained from GPC relative topolystyrene standards. The monomer reactivity ratio may have provided acompositional gradient.

Example 8:

Preparation of random copolymer of methyl methacrylate and butylacrylate

0.010 g of CuBr, 0.0322 g of 2,2'-bipyridyl and 0.010 ml ofethyl-2-bromoisobutyrate was added to a degassed mixture of methylmethacrylate (2.5 ml) and butyl acrylate (2.5 ml) and the reactionmixture was heated to 110° C. After 2.5 hrs., the polymerization wasinterrupted, and the resulting polymer was precipitated on methanol andpurified by reprecipitation from THF/methanol. The yield of thecopolymer was 53%.

The composition of the copolymer was determined by NMR to be 15% (bymoles) of butyl acrylate. Molecular weight, M_(n), of the copolymer was11,000 and polydispersity Mw/Mn=1.50, as obtained from GPC relative topolystyrene standards. The monomer reactivity ratio may have provided acompositional gradient.

Alternating and Partially Alternating Copolymers

Example 9:

Alternating copolymers isobutylene (IB)/methyl acrylate (molar feed3.5:1)

To 0.11 g (6.68×10⁻⁴ mole) 2,2'-bipyridyl and 0.036 g (2.34×10⁻⁴ mole)CuBr at -30° C. in a glass tube, were added 1.75 ml (2×10⁻² mole) IB,0.5 ml (0.55×10⁻² mole) methyl acrylate (MA) and 0.036 ml (2.34×10⁻⁴mole) 1-phenylethyl bromide under an argon atmosphere. The glass tubewas sealed under vacuum, and the reaction mixture was warmed at 50° C.for 48 hours. The reaction mixture was then dissolved in THF, andconversion of MA as determined by GC was 100%. The polymer was thenprecipitated in methanol (three times), filtered, dried at 60° C. undervacuum for 48 h and weighed. The content of IB in copolymer was 51%, andM_(n) =4050, M_(w) /M_(n) =1.46 (M_(th) =3400). The % of IB in thecopolymer as determined by integration of methoxy and gem-dimethylregions of the ¹ H-NMR spectrum was 44%. The tacticity of thealternating copolymer as calculated from the signals of methoxy protonsaccording to the method described by Kuntz (J. Polym. Sci. Polym. Chem.16, 1747, 1978) is rr/mr/mm=46/28/26. The glass transition temperatureof product as determined by DSC was -28° C.

Example 10:

IB/MA Copolymer (molar feed 1:1)

To 0.055 g (3.5×10⁻⁴ mole) 2,2'-bipyridyl and 0.017 g (1.17×10⁻⁴ mole)CuBr at -30° C. in a glass tube, were added 0.5 ml (0.55×10⁻² mole) IB,0.5 ml (0.55×10⁻² mole) methyl acrylate and 0.016 ml (1.17×10⁻⁴ mole)1-phenylethyl bromide under argon atmosphere. The glass tube was sealedunder vacuum and the reaction mixture was warmed at 50° C. for 24 hours.The reaction mixture was then dissolved in THF, and conversion of MA asdetermined by GC was 100%. The polymer was than precipitated in methanol(three times), filtered, dried at 60° C. under vacuum for 48 h andweighed. The content of IB in copolymer was 28% and Mn=6400, M_(w)/M_(n) =1.52 (M_(th) =6500). The % of IB in copolymer determined byintegration of methoxy and gem-dimethyl region of the ¹ H-NMR spectrumaccording to the method described by Kuntz was 26%. The glass transitiontemperature of the product as determined by DSC was -24° C.

Example 11:

IB/MA Copolymer (molar feed 1:3)

To 0.11 g (6.68×10⁻⁴ mole) 2,2'-bipyridyl and 0.036 g (2.34×10⁻⁴ mole)CuBr at -30° C. in a glass tube, were added 0.5 ml (0.55×10⁻² mole) IB,1.5 ml (1.65×10⁻² mole) methyl acrylate and 0.036 ml (2.34×10⁻⁴ mole)1-phenylethyl bromide under argon atmosphere. The glass tube was sealedunder vacuum and the reaction mixture warmed at 50° C. for 48 hours. Thereaction mixture was then dissolved in THF, and the conversion of MA asdetermined by GC was 100%. The polymer was then precipitated in methanol(three times), filtered, dried at 60° C. under vacuum for 48 h andweighed. The content of IB in the copolymer was 25%, and Mn=7570, M_(w)/M_(n) =1.58 (M_(th) =7400). The % of IB in copolymer as determined byintegration of methoxy and gem-dimethyl region of the ¹ H-NMR spectrumaccording to the method described by Kuntz was 24%. The glass transitiontemperature of the product as determined by DSC was -15° C.

Example 12:

Alternating copolymers of isobutyl vinyl ether (IBVE)/methyl acrylate(1:1)

To 0.055 g (3.51×10⁻⁴ mole) 2,2'-bipyridyl and 0.017 g (1.17×10⁻⁴ mole)CuBr in a glass tube, were added 0.6 ml (0.55×10⁻² mole) IBVE, 0.5 ml(0.55×10⁻² mole) methyl acrylate and 0.017 ml (1.17×10⁻⁴ mole)1-phenylethyl bromide under argon atmosphere. The glass tube was sealedunder vacuum, and the reaction mixture was warmed at 50° C. for 12hours. The reaction mixture was then dissolved in THF, and theconversion of MA and IBVE as determined by GC were 100%. The polymer wasthen precipitated in methanol (three times), filtered, dried at 60° C.under vacuum for 48 h and weighed. The content of IBVE in copolymer was51%, and M_(n) =8110, M_(w) /M_(n) =1.54 (M_(th) =8700). The glasstransition temperature of the product as determined by DSC was -31.3° C.

Example 13:

Copolymers of isobutyl vinyl ether/methyl acrylate (3:1)

To 0.11 g (6.68×10⁻⁴ mole) 2,2'-bipyridyl and 0.036 g (2.34×10⁻⁴ mole)CuBr in a glass tube, were added 1.8 ml (1.65×10⁻² mole) IBVE, 0.5 ml(0.55×10⁻² mole) methyl acrylate and 0.034 ml (2.34×10⁻⁴ mole)1-phenylethyl bromide under argon atmosphere. The glass tube was sealedunder vacuum, and the reaction mixture was warmed at 50° C. for 12hours. The reaction mixture was then dissolved in THF, and theconversion of MA and IBVE as determined by GC were 100%. The polymer wasthen precipitated in methanol (three times), filtered, dried at 60° C.under vacuum for 48 h and weighed. The content of IBVE in the copolymerwas 75%, and Mn=8710, M_(w) /M_(n) =2.00 (M_(th) =9090). The glasstransition temperatures of the product as determined by DSC were -44.3°C. and 7.1° C.

Example 14:

Copolymers of isobutyl vinyl ether/methyl acrylate (1:3)

To 0.11 g (6.68×10⁻⁴ mole) 2,2'-bipyridyl and 0.036 g (2.34×10⁻⁴ mole)CuBr in a glass tube, were added 0.6 ml (0.55×10⁻² mole) IBVE, 1.5 ml(1.65×10⁻² mole) methyl acrylate and 0.034 ml (2.34×10⁻⁴ mole)1-phenylethyl bromide under argon atmosphere. The glass tube was sealedunder vacuum, and the reaction mixture was warmed at 50° C. for 12hours. The reaction mixture was then dissolved in THF, and theconversion of MA and IBVE as determined by GC were 100%. The polymer wasthen precipitated in methanol (three times), filtered, dried at 60° C.under vacuum for 48 h and weighed. The content of IBVE in the copolymerwas 25%, and M_(n) =7860, M_(w) /M_(n) =1.90 (M_(th) =8400). The glasstransition temperatures of the product as determined by DSC were at-31.0° C. and 5.6° C.

Periodic Copolymers Example 15:

Under an argon atmosphere, 11.1 mL of styrene (9.6×10⁻² mole) was addedto 0.097 g (6×10⁻⁴ mole) of 2,2'-bipyridyl and 0.020 g (2×10⁻⁴ mole)CuCl in a 50 mL glass flask. The initiator 0.030 mL (2×10⁻⁴ mole)1-phenylethyl chloride was then added via syringe. The flask was thenimmersed in oil bath at 130° C. At various time intervals, samples fromthe reaction mixture were transferred to an NMR tube, and the conversionof styrene was determined.

Thereafter, 1.5 eq. of maleic anhydride (0.03 g, 3×10⁻⁴ mole) in benzene(4 mL) was injected into the flask at times of 20, 40, 60 and 80%conversion of styrene. After 25 hours, the reaction mixture was cooledto room temperature, and 15 mL of THF was added to the samples todissolve the polymers. The conversion of styrene by measuring residualmonomer was 95%.

The polymer was precipitated in dry hexane, filtered, dried at 60° C.under vacuum for 48 h and weighed. The product had a M_(n) =47500 andM_(w) /M_(n) =1.12 (M_(th) =50,000). The content of maleic anhydride wasdetermined by IR spectroscopy, and corresponded to the introducedamount.

Gradient Copolymers Example 16:

Preparation of a methyl acrylate/methyl methacrylate gradient copolymer

0.029 g of CuBr, 0.096 g of 2,2'-bipyridyl and 0.030 ml ofethyl-2-bromoisobutyrate were added to a degassed solution of methylacrylate (2.5 ml) and methyl methacrylate (2.0 ml) in ethyl acetate (2.0ml). The reaction mixture was thermostated at 90° C. and samples werewithdrawn after 3.0 hr, 5 hr, 7 hr and 23 hr. From the composition dataobtained from NMR measurements of these samples and from molecularweights evaluation from GPC measurements relative to polystyrenestandards, the compositional gradient along the chain of the finalcopolymer was calculated (FIGS. 3A-B). The final polymer (at 96%conversion) was purified by reprecipitation from methanol/THF.

Example 17:

0.125 g of CuBr, 0.407 g of 2,2'-bipyridyl and 0.118 ml ofethyl-2-bromoisobutyrate was added to a degassed mixture of methylacrylate (3.8 ml) and methyl methacrylate (4.8 ml). The reaction mixturewas thermostated at 80° C. and samples were withdrawn after 0.5 hr, 1 hrand 1.5 hr. From the composition data obtained from NMR measurements ofthese samples and from molecular weights evaluation from GPCmeasurements relative to polystyrene standards, the compositionalgradient along the chain of the final copolymer was calculated (FIGS.4A-B). The final polymer (at 88% conv.) was purified by reprecipitationfrom methanol/THF.

Example 18:

Preparation of a styrene/methyl methacrylate gradient copolymer

0.063 g of CuBr, 0.205 g of 2,2'-bipyridyl and 0.064 ml ofethyl-2-bromoisobutyrate was added to 5 ml of styrene and the mixturewas heated at 110° C. A mixture of styrene (5 ml) and methylmethacrylate (5 ml) was added at a rate of addition of 0.1 ml/min,followed by 10 ml of methyl methacrylate added at the same rate. Sampleswere withdrawn at certain time periods, and from the composition dataobtained from NMR measurements of these samples and from GPC measurementof the molecular weights relative to polystyrene standards, thecompositional gradient along the chain of the final copolymer wascalculated (FIGS. 5A-B). The final polymer (2.34 g) was purified byreprecipitation from methanol/THF. DSC measurements of the finalcopolymer show a single glass transition with T_(g) =106° C.

Example 19:

Preparation of methyl acrylate/methyl methacrylate gradient copolymer

0.107 g of CuBr, 0.349 g of 2,2'-bipyridyl and 0.109 ml ofethyl-2-bromoisobutyrate was added to a mixture of methyl acrylate (5ml) and methyl methacrylate (10 ml), and the reaction mixture was heatedto 90° C. Methyl acrylate (20 ml) was added to the reaction mixture at arate of addition of 0.1 ml/min. Samples were withdrawn at certain timeperiods, and from the composition data obtained from NMR measurements ofthese samples and from GPC measurement of the molecular weights relativeto polystyrene standards, the compositional gradient along the chain ofthe final copolymer was calculated (FIGS. 6A-B). The final polymer (3.15g) was purified by reprecipitation from methanol/THF. DSC measurementsof the final copolymer show a single glass transition with T_(g) =52° C.

Example 20:

Preparation of methyl acrylate/styrene gradient copolymers with varyinggradient of composition

0.063 g of CuBr, 0.205 g of 2,2'-bipyridyl and 0.64 ml ofethyl-2-bromoisobutyrate was added to 10 ml of styrene and the reactionmixture was heated to 95° C. Methyl acrylate was added to the reactionmixture at a rate of addition of 0.1 ml/min such that the final reactionmixture contained 90% of methyl acrylate. Samples were withdrawn atcertain time periods and from the composition data obtained from NMRmeasurements of these samples and from GPC measurement of the molecularweights relative to polystyrene standards, the compositional gradientalong the chain of the final copolymer was calculated (FIGS. 7A-B). Thefinal polymer (1.98 g) was purified by reprecipitation frommethanol/THF. DSC measurements of the final copolymer show a singleglass transition with T_(g) =58° C.

In a separate experiment, 0.063 g of CuBr, 0.205 g of 2,2'-bipyridyl and0.64 ml of ethyl-2-bromoisobutyrate was added to 10 ml of styrene andthe reaction mixture was heated to 95° C. Methyl acrylate was added tothe reaction mixture at a rate of addition of 0.085 ml/min such that thefinal reaction mixture contained 90% of methyl acrylate. Samples werewithdrawn at certain time periods. From the composition data obtainedfrom NMR measurements of these samples and from GPC measurement of themolecular weights relative to polystyrene standards, the compositionalgradient along the chain of the final copolymer was calculated (FIGS.8A-B). The final polymer (1.94 g) was purified by reprecipitation frommethanol/THF. DSC measurements of the final copolymer show a singleglass transition with T_(g) =72° C.

In a third experiment, 0.063 g of CuBr, 0.205 g of 2,2'-bipyridyl and0.64 ml of ethyl-2-bromoisobutyrate was added to 10 ml of styrene andthe reaction mixture was heated to 95° C. Methyl acrylate was added tothe reaction mixture at a rate of addition of 0.05 ml/min such that thefinal reaction mixture contained 90% of methyl acrylate. Samples werewithdrawn at certain time periods. From the composition data obtainedfrom NMR measurements of these samples and from GPC measurement of themolecular weights relative to polystyrene standards, the compositionalgradient along the chain of the final copolymer was calculated (FIGS.9A-B). The final polymer (3.08 g) was purified by reprecipitation frommethanol/THF. DSC measurements of the final copolymer show a singleglass transition with T_(g) =58° C.

Example 21:

Branched and Hyperbranched Polymers

Homopolymerizations were performed as follows: Typically,p-chloromethylstyrene, p-CMS, was polymerized in the presence of CuCl(1% relative to PCS) and 2,2'-bipyridyl (3%), at 110° C., under oxygenfree conditions, i.e., argon atmosphere. p-Chloromethylstyrene was addedto a flask containing CuCl/bipyridyl. Immediately upon addition ofp-CMS, a deep red, slightly heterogeneous solution was obtained. Heatingresulted in the color of the solution changing from red to green withinfifteen minutes of heating.

After a period of time the reaction was stopped and the sample dissolvedin THF. Conversion was determined by ¹ H NMR, and was found to begreater than 80%. The samples showed almost no observable change inviscosity at the reaction temperature, but cooling to room temperatureresulted in the sample becoming solid. The green copper(II) material wasremoved by passing the mixture through a column of alumina.Unprecipitated samples were analyzed by GPC relative to polystyrenestandards. The polymer was then purified by precipitation into methanolfrom THF. These samples were then analyzed by ¹ H NMR to determinemolecular weight. Table 9 outlines experimental results. All yields were>70%.

                  TABLE 9                                                         ______________________________________                                        Homopolymerization of p-Chloromethylstyrene                                   in the Presence of Cu (I) and 2,2'-Bipyridyl.sup.a                                             Conversion                                                   Temperature                                                                           Time (h) (%).sup.c M.sub.n.sup.d                                                                       M.sub.n.sup.e                                                                      M.sub.w /M.sub.n.sup.e                                                              M.sub.n.sup.f                     ______________________________________                                        125° C.                                                                        0.5      67        1900  1160 1.8   1070                              "       1.0      75        2250  1780 2.1   1870                              "       1.5      90        2940  2410 2.1   2480                              "       2.0      92        6280  2510 2.5   2750                               110° C..sup.b                                                                 24.0     96        2420  2100 1.3   --                                ______________________________________                                         .sup.a Bulk polymerization,  M!.sub.o  = 7.04 M,  CuC1!.sub.o  = 0.07 M,       bipy!.sub.o  = 0.21 M.                                                       .sup.b Solution polymerization in benzene,  M! = 3.52 M,  CuC1!.sub.o  =      0.035 M,  bipy!.sub.o  = 0.11 M.                                              .sup.c Conversion based on consumption of double bonds.                       .sup.d M.sub.n  determined by .sup.1 H NMR after precipitation.               .sup.e M.sub.n, M.sub.w  determined of entire sample, prior to                precipitation, by GPC, using linear polystyrene standards.                    .sup.f M.sub.n  by GPC, using linear polystyrene standards, after             precipitation into methanol/brine.                                       

Copolymerizations were carried out as follows: Styrene (18.18 g, 20 ml)was polymerized in a 50% w/v solution using p-dimethoxybenzene (20 g) assolvent. The amount of p-chloromethylstyrene was 2% (0.4 ml). The molarratio of p-chloromethylstyrene/CuCl (0.2594 g)/2,2'-bipyridyl (1.287 g)was 1:1:3. The solids were placed in a flask with a rubber septum andmagnetic stirrer, and degassed three times by vacuum and back fillingwith argon. Degassed monomer was added via syringe. The appropriateamount of p-chloromethyl-styrene was then added via syringe. Thereaction was heated to 130° C. The reaction was quenched byprecipitation into methanol. After 15 hours, conversion was 94.3% asdetermined by ¹ H NMR. Yield was 76%.

The sample was evaluated by SEC using relative calibration, and found tohave Mn=13400 and M_(w) =75000. By universal calibration, in conjunctionwith light scattering, the M_(n) =31,600 and M_(w) =164,500.

Methyl methacrylate (20 ml, 18.72 g) was used in place of styrene. Thereaction was run for 2 hours at 100° C. M_(n),SEC =44,700 and M_(w),SEC=112,400. M_(n) =58,700 (universal calibration), M_(w) =141,200 (lightscattering).

Cross-Linked Polymers and Gels Example 22:

Styrene (9.09 g, 10 ml) was polymerized in a 50% (w/vol.) solution usingp-dimethoxybenzene (10 g) as solvent. The amount ofp-chloromethylstyrene was 2% (0.2 ml). The molar ratio ofp-chloromethylstyrene/CuCl (0.1297 g)/2,2'-bipyridyl (0.6453 g) was1:1:3. The solids were placed in a flask with a rubber septum andmagnetic stirrer, and degassed three times by vacuum and back fillingwith argon. Degassed monomer was added via syringe.p-Chloromethylstyrene was then added via syringe. The reaction washeated to 130° C. The reaction was quenched by precipitation intomethanol. After 64.5 hours, conversion was 94.3% as determined by ¹ HNMR. Yield was 90%. A cloudy polymer solution was made in THF, but couldnot be passed through a 0.45 micron PTFE filter. Upon placing thesolution in a centrifuge for 26 hours at 7000 rpm, the solution wasclear with a slight layer of solid material at the bottom of the vial.The solution was passed through a 0.45 micron PTFE filter. M_(n)=118,000, M_(w) /M_(n) =3.74.

Example 23:

Styrene (9.09 g, 10 ml) was polymerized in a 50% (w/vol.) solution usingp-dimethoxybenzene (10 g) as solvent. The amount of p-CMS was 10% (0.2ml). The molar ratio of p-CMS/CuCl (0.1297 g)/2,2'-bipyridyl (0.6453 g)was 1:1:3. The solids were placed in a flask with a rubber septum andmagnetic stirrer, and degassed three times by vacuum and back fillingwith argon. Degassed monomer was added via syringe. p-Chloromethylstyrene was then added via syringe. The reaction was heated to 130° C.The reaction was quenched by precipitation into methanol. After 24hours, conversion was 94.3% as determined by ¹ H NMR. Yield was >90%.The polymer was stirred in THF but could not be dissolved. The polymersample was placed in a soxhlet apparatus under refluxing THF to removecopper salts.

The obtained sample was placed in THF and allowed to come toequilibrium. The gel was determined to have an equilibrium THF contentof 89%.

Example 24:

Difunctional Polymers

Polystyrene with two bromine or azide end groups were synthesized.

(A) α,ω-Dibromopolystyrene:

Styrene (18.18 g, 20 ml) was polymerized in a 50% (w/vol.) solutionusing p-dimethoxybenzene (20 g) as solvent. α,α'-Dibromo-p-xylene (1.848g) was used as the initiator. The molar ratio ofα,α'-Dibromo-p-xylene/styrene/CuBr (1.00 g)/2,2'-bipyridyl (3.28 g) was1:1:3. The solids were placed in a flask with a rubber septum andmagnetic stirrer, and degassed three times by vacuum and back fillingwith argon. Degassed monomer was added via syringe. The reaction washeated to 110° C. After 5.5 hours conversion was >95% as determined by ¹H NMR. The reaction was quenched by precipitation into methanol. Yieldwas >90%. The polymer was redissolved in THF and precipitated intomethanol three times. The polymer sample was dried under vacuum at roomtemperature overnight. Mn, as determined by comparison of the methineprotons adjacent to bromine and the aliphatic protons, was 2340. SEC,Mn=2440.

(B) αω-Diazidopolystyrene:

A sample of the above α,ω-dibromopolystyrene (5.0 g) was dissolved indry THF (20 ml) in the presence of tetrabutyl ammonium fluoride (1 mmolF⁻ /g) on silica gel (6.15 g). Trimethylsilyl azide (0.706 g, 0.81 ml)was then added via syringe. The solution was stirred for 16 hours underargon. ¹ H NMR showed complete conversion of the methine protonsadjacent to bromine to being adjacent to N₃. M_(n), by ¹ H NMR, was2340. Infrared spectroscopy showed a peak at 2080 cm⁻¹, whichcorresponds to the azide functional group.

A sample of the α,ω-diazidopolystyrene (4.7 mg) was placed in a DSCsample pan and was heated to 250° C. and held for 15 minutes. A seriesof endo and exothermic peaks were seen starting at 215° C. The samplewas allowed to cool and then dissolved in THF. The solution was injectedinto a SEC instrument. The Mn was 6500, a 250% increase in molecularweight. The distribution was broad, however.

Example 25:

Water Swellable Polymers

A: NVP/VAc-Cl Polymer:

N-vinylpyrrolidinone (50 ml, 48.07 g), vinyl chloroacetate (0.26 g, 0.25ml), and AIBN (0.7102 g) were combined in a 300 ml three-neck,round-bottom flask. The monomers were degassed by bubbling argon throughthe mixture. The mixture was heated to 60° C. for 1 h. The resultingsolid polymer was allowed to cool and then dissolved in THF. Thesolution was precipitated into hexanes, and the resulting polymerfiltered and dried at 70° C. under vacuum for three days.

(B): Hydrogel A:

The NVP/VAc-Cl polymer (5.0 g) of Example 25(A) was dissolved in styrene(20 ml), in the presence of CuCl (0.0411 g) and 4,4'-di-t-butyl-2,2'-bipyridyl (0.2224 g), under oxygen free conditions. The reactionmixture was heated to 130° C. After 30 minutes, the reaction mixturebecame gelatinous. The mixture was dissolved in DMF and precipitatedinto water. A gel-like mass was obtained and filtered. The resultingsolid was a gel weighing 20.0 g. The gel was dried over P₂ O₅ at 70° C.under vacuum for 2.5 days. Yield 4.0 g.

(C): Hydrogel B:

The NVP/VAc-Cl polymer (5.0 g) of Example 25(A) was dissolved in styrene(20 ml), in the presence of CuCl (0.0041 g) and4,4'-di-t-butyl-2,2'-bipyridyl (0.0222 g), under oxygen free conditions.The reaction mixture was heated to 130° C. After two hours, the reactionmixture became gelatinous. The reaction was stirred for three more hoursuntil the mixture was so viscous that the magnetic stir bar did notturn. The mixture was dissolved in DMF and precipitated into water. Agel-like mass was obtained and filtered. The resulting solid was a gelhaving a mass of 20.0 g. The gel was dried over P₂ O₅ at 70° C. undervacuum for 2.5 days. Yield 4.0 g.

(D): Macromonomers of Styrene

(i): Synthesis of Polystyrene with a Vinyl Acetate End Group(VAc-Styrene)

5K Polystyrene:

Cu(I)Cl (0.5188 g) and 2,2'-bipyridyl (2.40 g) were added to a 100 mlround bottom flask and sealed with rubber septum. The contents of theflask were placed under vacuum, then backfilled with argon. This wasrepeated two additional times. Diphenyl ether (30.0 ml), deinhibitedstyrene (30.0 ml) and vinyl chloroacetate (0.53 ml), all of which werepreviously degassed by bubbling argon through the liquids, were added tothe flask via syringe. The reaction mixture was then heated to 130° C.for 6 hours. The reaction mixture was then transferred into methanol toprecipitate the formed polymer. The precipitate was then twicereprecipitated from THF into methanol. The isolated white powder wasthen dried under vacuum at room temperature. Yield: 21.68 g (77.4%).GPC: M_(n) =4400, PD=1.22.

10K Polystyrene:

Cu(I)Cl (0.5188 g) and 2,2'-bipyridyl (2.40 g) were added to a 250 mlround bottom flask and sealed with a rubber septum. The contents of theflask were placed under vacuum, then backfilled with argon. This wasrepeated two additional times. Diphenyl ether (60.0 ml), deinhibitedstyrene (60.0 ml) and vinyl chloroacetate (0.53 ml), all of which werepreviously degassed by bubbling argon through the liquids, were added tothe flask via syringe. The reaction mixture was then heated to 130° C.for 24 hours. The reaction mixture was then transferred into methanol toprecipitate the formed polymer. The precipitate was then twicereprecipitated from THF into methanol. The isolated white powder wasthen dried under vacuum at room temperature. Yield: 44.36 g (81.3%).GPC: M_(n) =10,500, PD=1.25.

(ii): Synthesis of Water Swellable Polymers Copolymerization of N-VinylPyrrolidinone (75 wt. %) with VAc-Styrene (Mn=4400; 25 wt. %):

AIBN (0.0106 g) and VAc-styrene (2.50 g) were added to a 50 ml roundbottom flask and sealed with a rubber septum. The contents of the flaskwere placed under vacuum and backfilled with argon three times.Previously degassed DMSO (20.0 ml) and N-vinyl pyrrolidinone (7.5 ml)were added to the flask by syringe. The reaction was then heated to 60°C. for 20 hours. A highly viscous fluid was obtained and diluted withDMF (30.0 ml). The reaction mixture was precipitated into water. Theprecipitate was a swollen solid. This was filtered and dried undervacuum at 70° C. to produce the obtained polymer. The obtained polymerwas placed in a water bath for 3 days. The equilibrium water content was89%.

Copolymerization of N-Vinyl Pyrrolidinone (75 wt. %) with VAc-Styrene(Mn=10500. 25 wt. %)

AIBN (0.0106 g) and VAc-Styrene (2.50 g) were added to a 50 ml roundbottom flask and sealed with a rubber septum. The contents of the flaskwere placed under vacuum and backfilled with argon three times.Previously degassed DMSO (20.0 ml) and N-vinyl pyrrolidinone (7.5 ml)were added to the flask by syringe. The reaction was then heated to 60°C. for 20 hours. A highly viscous fluid was obtained and diluted withDMF (30.0 ml). The reaction mixture was precipitated into water. Theprecipitate was a white, jelly-like mass. The liquid was decanted, theprecipitate was air-dried overnight, and then dried under vacuum at 70°C. to produce the obtained polymer. M_(n) =116,000; PD=2.6.

After placing in a water bath for 3 days, the equilibrium water contentwas determined to be 89%.

Example 26:

Thiocyanate transfer polymerizations

It has been previously reported that thiocyanate (SCN) is transferredfrom Cu(SCN)₂ to an alkyl radical at roughly the same rate as chloridefrom CuCl₂ (Kochi et al, J. Am. Chem. Soc., 94, 856, 1972).

A 3:1:1 molar ratio of ligand (2,2'-bipyridyl bipy! or4,4'-di-n-heptyl-2,2'-bipyridyl dHbipy!) to initiator (PhCH₂ SCN) totransition metal compound (CuSCN) was used for each polymerization. Theinitiator system components were weighed and combined in air underambient conditions. The reactions were run in bulk according to theprocedure of Example 4, but at 120° C.

Reactions employing bipy were very viscous after 5 h, at which time theywere cooled to room temperature. Reactions employing dHbipy were notviscous after 5 h, and were therefore heated for 24 h before cooling toroom temperature. Results are shown in Table 10 below.

                  TABLE 10                                                        ______________________________________                                        Ligand    M/I    % Conv.      M.sub.n                                                                             PDI                                       ______________________________________                                        bipy      193    39           158,300                                                                             1.61                                      bipy      386    43           149,100                                                                             1.75                                      dHbipy    193    86            28,100                                                                             2.10                                      dHbipy    386    89            49,500                                                                             1.89                                      ______________________________________                                    

where "M/I" is the monomer/initiator ratio, "% Conv." refers to thepercent conversion, and "PDI" refers to the polydispersity.

The bipy reactions showed less than optimal molecular weight control,but the dhbipy reactions showed excellent molecular weight control. Itis believed that PDI can be improved further by increasing the amount orconcentration of Cu(II) at the beginning of polymerization.

Example 27:

Synthesis of comb-shaped PSt

The macro ATRP initiator, poly(p-chloromethylstyrene), PCMS, wassynthesized by polymerizing p-chloromethylstyrene (0.02 mol) in benzene(50%) at 60° C. for 24 hours using ICH₂ CN (0.0023 mol) and AIBN (0.0006mol). Yield: 92%. M_(n) =1150, M_(w) /M_(n) =1.20.

Subsequently, a degassed solution containing St (0.012 mol), purifiedPVBC (9.6×10⁻⁵ mol), CuCl (1.5×10⁻⁴ mol) and bipy (4.5×10⁻⁴ mol) washeated at 130° C. for 18 hrs. Comb-shaped PSt was obtained (yield=95%).M_(n) =18500, /M_(w) /M_(n) =1.40. At lower initial concentrations ofPCMS, higher molecular weight comb-shaped polystyrenes were formed(M_(n) =40,000 and 80,000 g/mol, as compared to linear polystyrenestandards, cf. the first three entries in Table 15).

Example 28:

Synthesis of PVAc-g-PSt

Vinyl acetate end-capped PSt (PSt-VAc) was synthesized by polymerizingSt (0.019 mol) in bulk at 130° C. for 18 h using ClCH₂ COOCH═CH2 (0.0018mol), CuCl (0.0018 mol) and bipy (0.0054 mol). Yield: 95%. Mn=1500,M_(w) /M_(n) =1.35.

Subsequently, a degassed solution containing vinyl acetate (5.8×10⁻³mol), purified PSt-VAc (6.67×10⁻⁵ mol) and AIBN (1×10⁻⁴ mol) in ethylacetate was heated at 60° C. for 48 h (ca. 85% conversion ofmacromonomer). Final grafting copolymer composition: Mn=54500, M_(w)/M_(n) =1.70.

Example 29:

End-Functional Polymers

One of the advantages of ATRP process is that one can synthesizewell-defined end-functional polymers by using functional alkyl halidesand transition metal species (Scheme 4). ##STR17##

Tables 11 and 12 report the characterization data of ATRP's of St usingvarious functional alkyl halides as initiators under typical ATRPexperimental conditions.

From Table 11, it appears that acid-containing alkyl halides give riseto relatively uncontrolled polymers (e.g., limited conversions, highermolecular weights than expected, and relatively broad molecular weightdistributions). This suggests that CuCl may react with these alkylhalides with formation of side products which disturb the "living" ATRPprocess.

Using 3-chloro-3-methyl-1-butyne, the monomer conversion was almostquantitative. However, the experimental molecular weight is ca. 3 timesas high as expected, and the polydispersity is as high as 1.95. Thissuggests that initiation is slow and the triple bond might also beattacked by the forming radicals.

In addition, using 2-(bromomethyl)naphthalene and9-(chloromethyl)anthracene as initiators, the polymers obtained showedproperties as good as polymers obtained by using 1-alkyl-2-phenylethylhalide initiators. However, 1,8-bis(bromomethyl)naphthalene does notseem to be as efficient an ATRP initiator as 2-(bromomethyl)naphthaleneand 9-(chloromethyl)anthracene under the same conditions.

More importantly, several Pst macromonomers containing polymerizabledouble bonds can be obtained in a controlled manner (Table 11). The ¹ HNMR spectrum of Pst initiated with vinyl chloroacetate in the presenceof 1 molar equiv. of CuCl and 3 molar equiv. of bipy at 130° C. showssignals at 4.0 to 5.5 ppm, assigned to vinylic end-groups. A comparisonof the integration of the vinylic protons with the protons in thebackbone gives a molecular weight similar to the molecular weightobtained from SEC; i.e., a functionality close to 0.90. This suggeststhat the double bond is unreactive towards a minute amount of St typeradicals during ATRP of St.

                                      TABLE 11                                    __________________________________________________________________________    ATRP Synthesis of End-Functional Polymers.sup.a                                                   Conv.                                                     RX              CuX %   M.sub.n,th..sup.b                                                                 M.sub.n, SEC                                                                      M.sub.w /M.sub.n                              __________________________________________________________________________    ClCH.sub.2 COOH CuCl                                                                              60  3000                                                                              12500                                                                             1.50                                          HC CC(CH.sub.3).sub.2 Cl                                                                      CuCl                                                                              95  4800                                                                              14100                                                                             1.90                                          ClCH.sub.2 CONH.sub.2                                                                         CuCl                                                                              70  3500                                                                              21300                                                                             1.70                                           ##STR18##      CuCl                                                                              92  4140                                                                              6730                                                                              1.35                                           ##STR19##      CuBr                                                                              96  1200                                                                              1010                                                                              1.35                                           ##STR20##      CuBr                                                                              99  5260                                                                              4300                                                                              1.25                                           ##STR21##      CuBr                                                                              75  1180                                                                              820 1.25                                          BrCH.sub.2 CHCH.sub.2                                                                         CuBr                                                                              99  5260                                                                              6500                                                                              1.23                                          "               CuBr                                                                              99  1000                                                                              970 1.23                                          ClCH.sub.2 COOCHCH.sub.2                                                                      CuCl                                                                              95  1000                                                                              1500                                                                              1.35                                          "               CuCl                                                                              98  3000                                                                              3150                                                                              1.30                                          "               CuCl                                                                              99  5000                                                                              5500                                                                              1.30                                          CH.sub.3 CHBrCOOCH.sub.2 CHCH.sub.2                                                           CuBr                                                                              90  4730                                                                              4580                                                                              1.40                                          __________________________________________________________________________     .sup.a Polymerization conditions: molar ratio of RX/CuX/Bpy: 1/1/3; temp:     ClATRP, 130° C.; BrATRP, 110° C.                                .sup.b Calculated based on M.sub.n = M.sub.o × (D M!/ RX!.sub.o).  

Example 30:

Sequential Block Copolymerization

ATRP can also be successfully used to produce well-defined di- andtri-block copolymers by means of sequential addition technique.

As seen in Table 12, di- and tri-block copolymers of St and MA obtainedare very well defined, regardless of monomer addition order. Themolecular weights are close to theoretical, and molecular weightdistributions remain very narrow, M_(w) /M_(n) from ˜1.0 to ˜1.25. SECtraces show that almost no first polymer contaminates the final blockcopolymer.

DSC measurements of several samples in Table 12 were also carried out.There appears to be two glass transition temperatures around 30° and100° C., very close to the Tg's of PMA and PSt, respectively. NMRanalysis of the purified polymer also shows the presence of PMA and PStsegments. All these results indicate that well-defined block copolymershave been synthesized.

                                      TABLE 12                                    __________________________________________________________________________    Synthesis of Di- and Tri- Block Copolymers Through                            Sequential Addition.sup.a                                                            M.sub.n, SEC                                                                        M.sub.w /M.sub.n                                                                  M.sub.n, calc.                                                                     M.sub.n, SEC                                                                        M.sub., NMR                                                                        M.sub.w /M.sub.n                             Monomer                                                                              (First                                                                              (First                                                                            (Co- (Co-  (Co- (Co-                                         Sequence                                                                             block)                                                                              block)                                                                            polymer)                                                                           polymer)                                                                            polymer)                                                                           polymer)                                     __________________________________________________________________________    PMA-PSt                                                                              6040  1.25                                                                               8920                                                                               8300 --   1.20                                         "      5580  1.20                                                                              10900                                                                              10580 --   1.12                                         "      15100 1.14                                                                              20700                                                                              21700 --   1.2                                          "      10000 1.25                                                                              21800                                                                              29000 27500                                                                              1.2                                          "      3900  1.25                                                                              18700                                                                              21400 --   1.13                                         PSt-PMA-PSt                                                                          9000  1.25                                                                              23800                                                                              26100 25500                                                                              1.40                                         "      12400 1.25                                                                              23800                                                                              24200 --   1.15                                         "      4000  1.25                                                                              12100                                                                              19200 18500                                                                              1.13                                         PMA-PSt-PMA                                                                          5300  1.13                                                                              12900                                                                              12600 --   1.25                                         "      7700  1.14                                                                              21700                                                                              21300 --   1.20                                         __________________________________________________________________________     .sup.a All polymerizations were carried out at 110° C.                 .sup.b Initiators used: diblock copolymer: 1phenylethyl bromide; triblock     copolymers: α,α'-dibromoxylene                               

ATRP is superior to living ionic polymerization for producingwell-controlled block copolymers. First of all, the experimentalconditions are relatively mild. Furthermore, cross-propagation isfacile, leading to block copolymerization regardless of monomer additionorder, as exemplified by the MA and St copolymerization above. Moreover,tri-block copolymers can be easily obtained by using a di-functionalinitiator. As expected, star-shaped block copolymers can be obtained byusing multi-functional alkyl halides.

Example 31:

Star-Shaped Polymer

(i) Synthesis of 4- and 6-arm star shaped PSt using1,2,4,5-tetrakis(bromomethyl)benzene and hexakis(bromomethyl)benzene asinitiator.

Table 13 lists the results regarding synthesis of four-arm and six-armstar-shaped PSt using 1,2,4,5-tetrakis(bromomethyl)benzene andhexakis(bromomethyl)benzene as initiator, respectively. The molecularweight distribution is fairly narrow, i.e., M_(w) /M_(n) <1.3 The M_(n)of these star-shaped polymers linearly increases with monomerconversion, indicating the presence of negligible amount of chain intransfer reactions (data not shown).

A key question involves whether the forming polymers have six or fourarms. Thus, ATRP of deuterated styrene was performed usinghexakis(bromomethyl)benzene as an initiator in the presence of 2 molarequiv. of CuBr and 6 molar equiv of bipy at 110° C., the sameexperimental conditions employed for synthesizing the six-arm PSt listedin Table 13. Except for the observation of a --CH₂ -- resonance at ca.1.55 ppm, the ¹ H NMR signals corresponding to --CH₂ Br, which usuallyresonate at ca. 5.0 ppm, cannot be detected at all in the ¹ H NMRspectrum of the PSt-d₈. This provides strong evidence that a six-armPSt-d₈ was produced.

                  TABLE 13                                                        ______________________________________                                        Synthesis of 4- and 6-Arm PSt Using C.sub.6 H.sub.2 (CH.sub.2 --Br).sub.4     and                                                                           C.sub.6 (CH.sub.2 --Br).sub.6 as Initiators at 110° C.                 Time, h  Yield, % M.sub.n, calc.                                                                           M.sub.n, SEC                                                                         M.sub.n /M.sub.n                          ______________________________________                                        4.75.sup.b                                                                             90        9000      12300  1.65                                       5.sup.b 90       27000      31100  1.29                                      71.sup.b 85       51200      62400  1.23                                      16.sup.c 92       13000      11800  1.30                                      16.sup.c 89       36400      28700  1.25                                      ______________________________________                                         .sup.a  R-Br!.sub.0 / CuBr!.sub.0 / bpy!.sub.0 = 1/2/6;                       .sup.b sixarm;                                                                .sup.c fourarm                                                           

(ii) Synthesis of 4- and 6-arm star-shaped PMA and PMMA using 1,2,4,5tetrakis(bromomethyl)benzene and hexakis(bromomethyl)benzene asinitiator

As noted in Table 14, 4- and 6-arm PMA and PMMA can also be synthesizedby using the same technique for star-shaped St polymerization. However,it may be advantageous to lower the concentration of the catalyst (e.g.,CuBr--bipy), otherwise gelation may occur at a relatively low monomerconversion.

This appears to confirm the radical process of ATRP. On the other hand,it also suggests that the compact structure of growing polymer chainsmay affect the "living" course of ATRP, since at the same concentrationof initiating system, MA and MMA ATRP represents a rather controlledprocess, when a mono-functional initiator was used.

                                      TABLE 14                                    __________________________________________________________________________    Synthesis of 4- and 6-Arm PMA and PMMA Using                                  C.sub.6 H.sub.2 (CH.sub.2 --Br).sub.4 and C.sub.6 (CH.sub.2 --Br).sub.6       as Initiator at 110° C.                                                R-Br/CuBr/bpy                                                                        polymer                                                                              Time, h                                                                            Yield, %                                                                           M.sub.n, calc                                                                      M.sub.n, SEC                                                                       M.sub.n /M.sub.w                            __________________________________________________________________________    1/2/6  C.sub.6 (PMA).sub.6                                                                  5    95   9500 10500                                                                              1.55                                        "      "      4    90   9000  9700                                                                              1.65                                        "      C.sub.6 (PMMA).sub.6                                                                 4.5  92   9100 12000                                                                              1.75                                        "      C.sub.6 H.sub.2 (PMA).sub.4                                                          25   gel  20000                                                                              --   --                                          "      C.sub.6 H.sub.2 (PMA).sub.4                                                          25   gel  40000                                                                              --   --                                          1/1/3  "      18   95   9500  6750                                                                              1.23                                        "      C.sub.6 H.sub.2 (PMMA).sub.4                                                         20   0.90 9000  9240                                                                              1.72                                        "      "      20   0.91 18200                                                                              17500                                                                              1.49                                        __________________________________________________________________________     .sup.a Polymerization at 110° C.                                  

Example 32:

Graft Technique

Well-defined comb-shaped PSt has been successfully obtained using PCMSas an ATRP initiator. Table 15 shows the SEC results of final polymers.The MWD is rather narrow.

                  TABLE 15                                                        ______________________________________                                        Synthesis of Graft Copolymers Using PCMS (DP.sub.n = 11)                      as Initiator.sup.a                                                            Monomer Time, hr Yield, %    M.sub.n, SEC                                                                         M.sub.w /M.sub.n                          ______________________________________                                        St.sup.b                                                                              18       95          18500  1.40                                      St.sup.b                                                                              18       90          38500  1.35                                      St.sup.b                                                                              18       85          80500  1.54                                      BA      15       95          18400  1.60                                      MMA     15       95          37700  1.74                                      BA.sup.c                                                                              22       90          24000  1.46                                      MMA.sup.c                                                                             22       90          46500  1.47                                      MMA.sup.c                                                                             22       85          51100  1.44                                      ______________________________________                                         .sup.a Polymerization at 130° C. in bulk.                              .sup.b Taken from Example 27.                                                 .sup.c Polymerization in 50% ethyl acetate solution.                     

Similar to 4- and 6-arm polymers, a key question is whether all chlorineatoms in PCMS participate in the ATRP. A comparison of the ¹ H NMRspectra of PCMS and PSt-d₈ -g-PCMS shows that the resonances at ca. 5ppm, corresponding to CH₂ Cl in PCMS, completely disappear, suggestingthe formation of pure PSt comb-copolymer.

Example 33:

Synthesis of ABA Block Copolymers with B=2-Ethylhexyl Acrylate

(a) Synthesis of Center B Block (α,ω-Dibromopoly(2-ethylhexyl acrylate))

To a 50 ml round bottom flask, CuBr (0.032 g), dTBiby (0.129 g) andα,α'-dibromo-p-xylene (0.058 g) were added. The flask was then sealedwith a rubber septum. The flask was degassed by applying a vacuum andbackfilling with argon. Degassed and deinhibited racemic 2-ethylhexylacrylate (10.0 ml) was then added via syringe. Degassed diphenyl ether(10.0 ml) was also added by syringe. The reaction was heated to 100° C.and stirred for 24 hours. Conversion by ¹ H NMR was >90%. M_(n) =40,500;M_(w) /M_(n) =1.35.

(b) A=Methyl Methacrylate

To the reaction mixture obtained in Example 33(a) containing thepoly(2-ethylhexyl acrylate), methyl methacrylate (4.53 ml) was added bysyringe. The reaction was stirred at 100° C. for 8 hours. Conversion ofMMA>90%. Mn (overall)=58,000; M_(w) /M_(n) =1.45.

(c) A=Acrylonitrile

The experiment of Example 33(a) was repeated. To the reaction mixturecontaining the (2-ethylhexyl acrylate) (M_(n) =40,500; M_(w) /M_(n)=1.35), acrylonitrile (5.44 ml) was added by syringe. The reaction wasstirred at 100° C. for 72 hours. Conversion of acrylonitrile=35%. M_(n)(overall)=47,200; M_(w) /M_(n) =1.45.

Example 34:

Synthesis of MMA-BA-MMA Block Copolymer Synthesis ofα,ω-dibromopoly(butyl acrylate):

To a 50 ml round bottom flask, α,α'-dibromo-p-xylene (0.0692 g), CuBr(0.0376 g), and 2,2'-bipyridyl (0.1229 g) were added and sealed with arubber septum. The flask was then evacuated and filled with argon threetimes. Previously degassed butyl acrylate (15.0 ml) and benzene (15.0ml) were added via syringe. The reaction was heated to 100° C. for 48hours, after which time the conversion was 86.5%, as determined by ¹ HNMR. The reaction mixture was poured into cold methanol (-78° C.) toprecipitate the polymer. The precipitate was filtered. The obtainedsolid was a tacky, highly viscous oil. M_(n) =49,000, M_(w) /M_(n)=1.39.

Synthesis of poly(MMA-BA-MMA):

In a round bottom flask, α,ω-dibromopoly(butyl acrylate) (2.0 g), CuBr(0.0059 g), 2,2'-bipyridyl (0.0192 g) and dimethoxybenzene (2.0 g) wereadded. The flask was sealed with a rubber septum and placed under anargon atmosphere as described above for the synthesis ofα,ω-dibromopoly(butyl acrylate). Degassed methyl methacrylate (0.73 ml)was added via syringe. The reaction was heated to 100° C. for 5.25hours. The conversion was determined to be 88.8% by ¹ H NMR. Thereaction mixture was poured into methanol to precipitate the polymer.The solid which was obtained was colorless and rubbery. M_(n) =75,400,M_(w) /M_(n) =1.34.

Example 35:

Synthesis of poly(p-t-butylstyrene)

To a 100 ml round bottom flask, dimethoxybenzene (25.0 g), CuCl (0.2417g) and 2,2'-bipyridyl (1.170 g) were added and sealed with a rubberseptum. The flask was then evacuated and filled with argon three times.Degassed t-butylstyrene (28.6 ml) and 1-phenylethyl chloride (0.33 ml)were added via syringe. The reaction was then heated to 130° C. for 8.5hours. The reaction mixture was precipitated into methanol, filtered anddried. M_(n) =5531. M_(w) /M_(n) =1.22.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and is desired to be secured by Letters PATENT ofthe United States is:
 1. A controlled free radical polymerizationprocess, of atom or group transfer radical polymerization, comprisingthe steps of:radically polymerizing one or more radically(co)polymerizable monomers in the presence of a system comprising: aninitiator having one or more radically transferable atoms or groups, atransition metal compound which participates in a reversible redox cyclewith said initiator or a dormant polymer chain end, and in its redoxconjugate form with a growing polymer chain end radical, an amount ofthe redox conjugate of the transition metal compound sufficient todeactivate at least some initially-formed radicals, wherein thetransition metal compound and the redox conjugate are present in amountsproviding a transition metal compound:redox conjugate molar ratio offrom 99.9:0.1 to 0.1:99.9, and any N-, O-, P- or S- containing ligandwhich coordinates in a σ-bond to the transition metal, anycarbon-containing ligand which coordinates in a π-bond to the transitionmetal or any carbon-containing ligand which coordinates in acarbon-transition metal a-bond but which does not form a carbon-carbonbond with said monomer under the polymerizing conditions, wherein saidtransition metal compound and said ligand are matched with one anotherin order to provide reaction with said initiator to reversibly generatea radical; to form a (co)polymer.
 2. The process of claim 1, furthercomprising the step of adding said redox conjugate to a reaction vesselprior to said polymerizing step.
 3. The process of claim 1, furthercomprising the step of exposing said transition metal compound to oxygenfor a length of time sufficient to form said redox conjugate.
 4. Theprocess of claim 1, wherein said polymerizing is conducted in an aqueousmedium.
 5. The process of claim 1, wherein said transition metalcompound participates in a reversible redox cycle with said initiatorand said (co)polymer.
 6. The process of claim 1, wherein said initiatorcomprises a compound of the formula: ##STR22## wherein: X is selectedfrom the group consisting of Cl, Br, I, OR¹⁰, SR¹⁴, SeR¹⁴, OC(═O)R¹⁴,OP(═O)R¹⁴, OP(═O)(OR¹⁴)₂, OP(═O)OR¹⁴, O--N(R¹⁴)₂, S--C(═S)N(R¹⁴)₂, CN,NC, SCN, CNS, OCN, CNO and N₃, whereR¹⁰ is alkyl of from 1 to 20 carbonatoms in which each of the hydrogen atoms may be independently replacedby halide, alkenyl of from 2 to 20 carbon atoms, alkynyl of from 2 to 20carbon atoms, phenyl or aralkyl which may be substituted with from 1 to5 halogen atoms or alkyl groups of from 1 to 4 carbon atoms, and R¹⁴ isindependently aryl or a straight or branched C₁ -C₂₀ alkyl group, orwhere an N(R¹⁴)₂ group is present the two R¹⁴ groups may be joined toform a 5-, 6- or 7 membered heterocyclic ring; R¹¹, R¹² and R¹³ are eachindependently selected from the group consisting of H, halogen, C₁ -C₂₀alkyl, C₃ -C₈ cycloalkyl, C(═Y)R⁵, C(═Y)NR⁶ R⁷, COCl, OH, CN, C₂ -C₂₀alkenyl or alkynyl, oxiranyl, glycidyl, aryl, heterocycyl, aralkyl,aralkenyl, C₂ -C₆ alkylene or alkenylene substituted with oxiranyl orglycidyl, C₁ -C₆ alkyl in which from 1 to all of the hydrogen atoms arereplaced with halogen, and C₁ -C₆ alkyl substituted with from 1 to 3substituents selected from the group consisting of C₁ -C₄ alkoxy, aryl,heterocyclyl, C(═Y)R⁵, C(═Y)NR⁵ R⁷ (where R⁶ and R⁷ are as definedabove), oxiranyl and glycidyl; whereR⁵ is alkyl of from 1 to 20 carbonatoms, alkylthio of from 1 to 20 carbon atoms, or 24 (where R²⁴ is H oran alkali metal), alkoxy of from 1 to 20 carbon atoms, aryl, aralkyl,heterocyclyl, aryloxy or heterocyclyloxy; R⁶ and R⁷ are independently Hor alkyl of from 1 to 20 carbon atoms, or R⁶ and R⁷ may be joinedtogether to form an alkylene group of from 2 to 7 carbon atoms, thusforming a 3- to 8-membered ring, and R⁸ is H, straight or branched C₁-C₂₀ alkyl or aryl; m is O or 1; and n is 0, 1 or 2 wherein when R¹¹,R¹² and R¹³ are other than hydrogen or halogen, each can, independently,be substituted with an X group as defined above.
 7. The process of claim1, wherein said ligand has a formula selected from the group consistingof

    R.sup.16 --Z--R.sup.17

    R.sup.16 --Z--(R.sup.18 --Z).sub.m --R.sup.17 and

    R.sup.20 R.sup.21 C(C(═Y)R.sup.5).sub.2

where: R¹⁶ and R¹⁷ are independently selected from the group consistingof H, C₁ -C₂₀ alkyl, aryl, heterocyclyl, and C₁ -C₆ alkyl substitutedwith C₁ -C₆ alkoxy, C₁ -C₄ dialkylamino, C(═Y)R⁵, C(═Y)R⁶ R⁷ and/orYC(═Y)R⁸, or R¹⁶ and R¹⁷ can be joined to form a saturated, unsaturatedor heterocyclic ring, whereY is NR⁸, S or O, R⁵ is alkyl of from 1 to 20carbon atoms, alkylthio of from 1 to 20 carbon atoms, OR²⁴ (where R²⁴ isH or an alkali metal), alkoxy of from 1 to 20 carbon atoms, aryl,aralkyl, heterocyclyl, aryloxy or heterocyclyloxy, R⁶ and R⁷ areindependently H or alkyl of from 1 to 20 carbon atoms, or R⁶ and R⁷ maybe joined together to form an alkylene group of from 2 to 7 carbonatoms, thus forming a 3- to 8-membered ring, andR⁸ is H, straight orbranched C₁ -C₂₀ alkyl or aryl; each R¹⁸ is independently a divalentgroup selected from the group consisting of C₂ -C₄ alkylene and C₂ -C₄alkenylene where the covalent bonds to each Z are at vicinal positionsor at β-positions, and C₃ -C₈ cycloalkanediyl, C₃ -C₈ cycloalkenediyl,arenediyl and heterocyclylene where the covalent bonds to each Z are atvicinal positions; Z is O, S, NR¹⁹ or PR¹⁹, where R¹⁹ is selected fromthe same group as R¹⁶ and R¹⁷ ; each of R²⁰ and R²¹ is independentlyselected from the group consisting of H, halogen, C₁ -C₂₀ alkyl, aryland heterocyclyl, and R²⁰ and R²¹ may be joined to form a C₃ -C₈cycloalkyl ring or a hydrogenated aromatic or heterocyclic ring; and mis from 1 to 6; where at least one of R¹⁶ and R¹⁷ or at least one of R²⁰and R²¹ are C₂ -C₂₀ alkyl, C₁ -C₆ alkyl substituted with C₁ -C₆ alkoxyand/or C₁ -C₄ dialkylamino, or are aryl or heterocyclyl substituted withat least one aliphatic substituent selected from the group consisting ofC₁ -C₂₀ alkyl, C₂ -C₂₀ alkenyl, C₂ -C₂₀ alkynyl and alkyl-substitutedaryl such that at least two carbon atoms are members of the aliphaticsubstituent(s).
 8. A process of controlled free radical polymerizationby atom or group transfer radical polymerization, comprising the stepsof:polymerizing one or more radically (co)polymerizable monomers in ahomogeneous reaction medium comprising: an initiator having one or moreradically transferable atoms or groups, a transition metal compoundwhich participates in a reversible redox cycle with said initiator or adormant polymer chain end, and any N-, O-, P- or S- containing ligandwhich coordinates in a σ-bond to the transition metal, anycarbon-containing ligand which coordinates in a π-bond to the transitionmetal or any carbon-containing ligand which coordinates in acarbon-transition metal σ-bond but which does not form a carbon-carbonbond with said monomer under the polymerizing conditions, wherein saidtransition metal compound and said ligand are matched with one anotherin order to provide reaction with said initiator to reversibly generatea radical, and wherein said transition metal compound and said ligandare selected in order to render the transition metal complex thus formedsoluble in the homogeneous reaction medium; to form a (co)polymer.
 9. Aprocess for preparing a graft copolymer, comprising the process of claim1, wherein said initiator is a (co)polymer macroinitiator having one ormore radically transferable atoms or groups.
 10. The process of claim 9,further comprising the step of preparing said (co)polymermacroinitiator.
 11. A process for preparing a graft copolymer,comprising:preparing a (co)polymer macroinitiator having one or moreradically transferable atoms or groups by a conventional polymerizationprocess, grafting from said (co)polymer macroinitiator one or morefurther (co)polymer chains or blocks by the process of claim 1 to form agraft (co)polymer.
 12. The process of claim 1, wherein said process isperformed in bulk.
 13. The process of claim 1, wherein said process isperformed in an inorganic medium.
 14. The process of claim 1, whereinthe N-, O-, P- or S- containing ligand which coordinates in a π-bond tothe transition metal is chosen to render the transition metal complexthus formed soluble in the polymerization medium.
 15. The process ofclaim 1, wherein said one or more radically polymerizable monomers isadded continuously to the polymerization process.
 16. The process ofclaim 8, wherein the N-, O-, P- or S- containing ligand whichcoordinates in a π-bond to the transition metal is chosen to render thetransition metal complex thus formed soluble in the polymerizationmedium.
 17. The process of claim 8, wherein said one or more radicallypolymerizable monomers is added continuously to the polymerizationprocess.
 18. The process of claim 1, wherein said one or more radicallypolymerizable monomers is added in portions to the polymerizationprocess.
 19. The process of claim 8, wherein said one or more radicallypolymerizable monomers is added in portions to the polymerizationprocess.
 20. The process of claim 1, wherein said one or more radicallypolymerizable monomers comprise a first vinyl monomer and a second vinylmonomer, wherein said first vinyl monomer is an electron donor and saidsecond vinyl monomer is an electron acceptor.
 21. The process of claim1, wherein said initiator is formed in situ by reaction of aconventional free radical generating compound with a transition metalcompound present in a higher of two available oxidation states for saidtransition metal compound, such that a radically transferable atom orgroup is transferred from the transition metal compound to a freeradical generated by said conventional free radical generating compoundto form said initiator.
 22. The process of claim 8, wherein said one ormore radically polymerizable monomers comprise a first vinyl monomer anda second vinyl monomer, wherein said first vinyl monomer is an electrondonor and said second vinyl monomer is an electron acceptor.
 23. Theprocess of claim 8, wherein said initiator is formed in situ by reactionof a conventional free radical generating compound with a transitionmetal compound present in a higher of two available oxidation states forsaid transition metal compound, such that a radically transferable atomor group is transferred from the transition metal compound to a freeradical generated by said conventional free radical generating compoundto form said initiator.
 24. The process of claim 1 wherein thetransition metal compound is added to the monomers a sufficient amountof time prior to addition of the initiator to allow any dissolved oxygento react with the transition metal compound and form the redox conjugateof the transition metal compound.